https://web.phys.virginia.edu/Private/Covid-19/colloquium.asp
Friday, December 3, 2021
3:30 PM
Physics Building, Room 204
Note special room.
"Floquet-engineering topological Dirac bands in an optical lattice"
Ian Spielman , NIST and The University of Maryland
[Host: Prof. Dima Pesin]
Over the years my group has performed a number of experiments realizing relativistic physics using cold atoms — described by the 1D Dirac Hamiltonian in some degree of approximation. I will begin by reviewing these results in conjunction with those from the whole of the cold-atom community.
With that backdrop, I describe a spin dependent bipartite Floquet lattice, in which the dispersion relation is linear for all points in the Brillouin zone. The (stroboscopic) Floquet spectrum of our periodically-driven Hamiltonian features perfect spin-momentum locking, and a linear Dirac dispersion. These bands are protected by a Floquet topological invariant which we directly measure by using quantum state tomography.
https://web.phys.virginia.edu/Private/Covid-19/colloquium.asp
Friday, November 19, 2021
3:30 PM
Physics Building, Room 204
Note special room.
"Analogue gravity in cold atom and condensed matter systems "
Professor Daniel Sheehy , Louisiana State University
[Host: Cass Sackett]
In recent years there has been much interest in the field of "analogue gravity", in which cosmological or astrophysical phenomena like Hawking radiation are mimicked in a laboratory experiment. At LSU, my research group in cold atom/condensed matter theory became interested in this field, motivated by the recent experiment of Eckel and collaborators, [Phys. Rev. X 8, 021021 (2018)] who used a rapidly expanding Bose-Einstein condensate (BEC) to reproduce the inflationary regime of the early universe. I will present our work on the physics of inflation in expanding BEC's, and discuss other setups to detect analogue gravity phenomena like the Unruh effect.
https://web.phys.virginia.edu/Private/Covid-19/colloquium.asp
Friday, November 12, 2021
3:30 PM
Physics Building, Room 204
Note special room.
"Physics motivations for future colliders"
Professor Tao Han , University of Pittsburg
[Host: Professor P.Q. Hung]
With the milestone discovery of the Higgs boson at the CERN Large Hadron Collider (LHC), high energy physics has entered a new era. The completion of the “Standard Model” (SM) implies, for the first time ever, that we have a relativistic, quantum-mechanical, self-consistent theoretical framework, conceivably valid up to exponentially high energies, even to the Planck scale. Yet, the SM leaves many unanswered questions both from the theoretical and observational perspectives, including the nature of the electroweak superconductivity and its phase transition, the hierarchy between the particle masses and between the observed scales, the nature of dark matter etc. There are thus compelling reasons to believe that new physics beyond the SM exists. We argue that the collective efforts of future high energy physics programs, in particular the future colliders, hold great promise to uncover the laws of nature to a deeper level.
https://web.phys.virginia.edu/Private/Covid-19/colloquium.asp
Friday, November 5, 2021
3:30 PM
Physics Building, Room 204
Note special room.
"Atomtronics for Quantum Sensing"
Professor Malcolm Boshier , Los Alamos National Lab
[Host: Prof. Cass Sackett]
Atomtronics is the emerging technology of building circuits where the current is a flow of ultracold atoms propagating as coherent matter waves inside suitable waveguides. In this talk I will describe our atomtronic technology in which the waveguides are created with laser light via the optical dipole potential, and then discuss two quantum sensors based on it. First, we have demonstrated the atomtronic analogue of the dc SQUID and shown that it exhibits the quantum interference that gives the Superconducting Quantum Interference Device its name. In the conventional SQUID this is seen as a periodic variation of critical current with magnetic flux. In the atomtronic SQUID it causes a periodic variation of critical current with rotation, enabling the device to function as a gyro. Second, we are developing an atomtronic version of the Fiber Optic Gyro, in which rotation is measured by the Sagnac effect. In our device a Bose-Einstein condensate is split, reflected, and recombined inside a waveguide that is translated so that the wavepackets travel around a loop and realize a waveguide Sagnac atom interferometer.
https://web.phys.virginia.edu/Private/Covid-19/colloquium.asp
Friday, October 29, 2021
3:30 PM
Physics Building, Room 204
Note special room.
"Exploring Gravitational Wave and Dark Matter Physics with the 100-meter-tall MAGIS-100 Atom Interferometer"
Professor Tim Kovachy , Northwestern University
[Host: Prof. Bob Hirosky]
Atom interferometers exploit spatially delocalized quantum states to make a wide variety of highly precise measurements. Recent technological advances have opened a path for atom interferometers to contribute to multiple areas at the forefront of modern physics, including searches for wave-like dark matter, gravitational wave detection, and fundamental quantum science. In this colloquium, I will describe MAGIS-100, a 100-meter-tall atom interferometer being built at Fermilab to pursue these directions. MAGIS-100 will serve as a prototype gravitational wave detector in a new frequency range, between the peak sensitivities of LIGO and LISA, that is promising for pursuing cosmological signals from the early universe and for studying a broad range of astrophysical sources. In addition, MAGIS-100 will search for wave-like dark matter, probe quantum mechanics in a new regime in which massive particles are delocalized over macroscopic scales in distance and time, and act as a testbed for advanced quantum sensing techniques. Finally, I will discuss the potential and motivation for follow-on atomic detectors with even longer baselines.
https://web.phys.virginia.edu/Private/Covid-19/colloquium.asp
Friday, October 22, 2021
3:30 PM
Physics Building, Room 204
Note special room.
"Quantum Many-Body Physics of Superconducting Qubits"
Professor Leonid Glazman , Yale University
[Host: Dima Pesin]
The ongoing development of superconducting qubits has brought some basic questions of many-body physics to the research forefront, and helped solve several of them. I will address two effects in quantum condensed matter highlighted by the development of a fluxonium qubit. The first one is the so-called cosine-phi problem stemming from the seminal paper of Brian Josephson. It predicted the phase dependence of the dissipative current across the Josephson junction. A fluxonium qubit enabled the observation of the effect, after nearly 50 years of unsuccessful attempts by other techniques. The second one is inelastic scattering ("splitting") of a microwave photon by quantum fluctuations of phase across a Josephson junction. This effect is the elementary mechanism driving the Schmid transition, which predicts a collapse of the Josephson current in a junction influenced by a dissipative environment.
https://web.phys.virginia.edu/Private/Covid-19/colloquium.asp
Friday, October 8, 2021
3:30 PM
Physics Building, Room 204
Note special room.
" Muon magnetic anomaly: probing the innermost nature of vacuum"
Professor Dinko Pocanic , University of Virginia - Department of Physics
[Host: Prof. Gordon Cates]
Marking the semi-anniversary of the Fermilab Muon g−2 experiment (E989) Run 1 result, this colloquium will review the current status of the muon magnetic anomaly, the inferred evidence of possible particles outside the Standard Model (SM), and future prospects in this active research field.
The intrinsic magnetic field of a simple object, such as a compass needle, is expressed in terms of its magnetic moment. The magnetic moment of a point particle, such as the electron, is predicted by relativistic quantum mechanics to be g = 2, in convenient dimensionless units. For the electron, this prediction fails at the part-per-thousand level; the resulting magnetic anomaly, ae = (g − 2)/2, is due to the electron’s couplings to virtual particles excited in the vacuum.
Muon, the electron’s 200 times heavier cousin, experiences far stronger couplings to massive virtual particles, including possible non-SM exotics. The SM provides a prediction for the muon magnetic anomaly aµ with sub-ppm precision. Hence, a comparably precise measurement of aµ offers a uniquely sensitive test for the presence of non-SM particles in nature. For almost 20 years a tantalizing discrepancy of ∼ 3 – 4σ has persisted between the measurements of aµ, and the SM calculations. The Fermilab Muon g−2 Run 1 result brings a much awaited update to this test, with much more to come.
Attend virtually via Zoom:
https://web.phys.virginia.edu/Private/Covid-19/colloquium.asp
Friday, October 1, 2021
3:30 PM
Physics Building, Room 204
Note special room.
"Rotation sensing with an atom-interferometer gyroscope"
Professor Cass Sackett , University of Virginia - Department of Physics
[Host: Gordon Cates]
Precision rotation sensing is useful for navigation, geophysics, and tests of fundamental physics. Atom interferometers provide, by some measures, the most sensitive method for rotation sensing achieved to date. However, the best performance requires freely falling atoms in a large experimental apparatus. Many applications, such as navigating a vehicle, will benefit from a more compact geometry. One method to achieve this is by using trapped atoms that are suspended against gravity. We have implemented such an interferometer and used it to measure a rotation rate comparable to that of the Earth. The most recent iteration of the interferometer has demonstrated improvements by a factor of ten in rotation sensitivity and trap stability. A second new apparatus reduces the scale of the vacuum chamber and optical system to roughly the size of a microwave oven.
Attend virtually via Zoom:
https://web.phys.virginia.edu/Private/Covid-19/colloquium.asp
Friday, September 17, 2021
3:30 PM
Physics Building, Room 204
Note special room.
"Inside the Proton: science fact, speculation, and the stuff of science fiction"
Professor Gordon Cates , University of Virginia - Department of Physics
[Host: Kent Paschke]
Whereas the structure of the atom has been understood for many years, the internal structure of the proton (and neutron) is the subject of active research. Understanding the nucleon is difficult because its structure is governed by quantum chromodynamics, or QCD, which has not been solved exactly in the non-perturbative or low-energy regime. The proton's structure is intriguing, however, for many reasons. For example, we think of the proton as being made of three quarks, but the mass of those quarks only accounts for about 1% of the proton's mass. The remaining 99%, and hence 99% of the known mass in the universe, is due to exotic effects associated with the QCD vacuum. While a great deal of work remains to be done, the way in which we visualize the proton has changed dramatically since the discovery of quarks. Just as the structure of the atom was unveiled early in the 20th century, the structure of the proton is being unveiled in the first decades of the 21st century. Another intriguing aspect of the proton arises from the fact that QCD is the only theory in nature that has essentially no free parameters. String theory, that attempts to unify our understanding of gravity and the quantum world, grew out of early efforts to understand the strong interaction. Since string theory deals with the topology of space and time, it is tempting to believe that a deep understanding of the proton may one day provide a window into even more fundamental questions. The colloquium will cover some recent developments in our understanding of the nucleon, as well as providing a glimpse of where this rich area of research is heading in upcoming years.
Attend virtually via Zoom:
https://web.phys.virginia.edu/Private/Covid-19/colloquium.asp
Friday, September 10, 2021
3:30 PM
Physics Building, Room 204
Note special room.
"Stirring by staring: Induced non-equilibrium states by measurements in quantum systems"
Israel Klich , University of Virginia - Department of Physics
[Host: Despina Louca]
In quantum mechanics, the role of an observer is fundamentally different from that of a classical observer. The quantum mechanical observer necessarily plays an active role in the dynamics of the system that it is observing. This apparent difficulty may be turned into a tool to drive an initially trivial system into a complicated quantum many-body state simply by observing it. I will present two remarkable examples of states induced by measurement. In the first, we examine the role of a moving density measuring device interacting with a system of fermions, and in particular, show that it would leave behind a wake of purely quantum origin. In the second example, inspired by the recent invention of topological Floquet insulators, we will see how a suitably chosen set of density measurements, repeated periodically, will induce robust chiral edge motion on a lattice of free fermions. Our examples show how quantum mechanical observation can be added as a versatile tool to the arsenal of quantum engineering in condensed matter systems.
https://web.phys.virginia.edu/Private/Covid-19/colloquium.asp
Friday, February 12, 2021
2:00 PM
Online, Room via Zoom
Note special time.
Note special room.
"Complexity of magnetic patterns and self-induced spin-glass state"
Prof. Mikhail Katsnelson , Radboud University of Nijmegen, The Netherlands,
[Host: Dima Pesin]
The origin of complexity remains one of the most important and, at the same time, the most controversial scientific problems. Earlier attempts were based on theory of dynamical systems but did not lead to a satisfactory solution of the problem. I believe that a deeper understanding is possible based on a recent development of statistical physics, combining it with relevant ideas from evolutionary biology and machine learning.
Using patterns in magnetic materials as the main example, I discuss some general problems such as (a) a formal definition of pattern complexity [1]; (b) self-induced spin glassiness due to competing interactions as a way to interpret chaotic patterns [2]; (c) multi-well states intermediate between glasses and ordinary ordered states and their relevance for the problem of long-term memory in complicated systems [3]; and (d) complexity of frustrated quantum spin systems [4]. I will also review a very recent experimental observation of self-induced spin-glass state in elemental neodymium [5].
https://web.phys.virginia.edu/Private/Covid-19/colloquium.asp
Friday, February 5, 2021
3:30 PM
Physics Building, Room via Zoom
Note special room.
"A fermionic triangular-lattice quantum gas microscope "
Peter Schauss , University of Virginia - Physics Dept.
[Host: Bob Jones]
Geometrically frustrated many-body systems show many interesting emerging phenomena, ranging from kinetic frustration to exotic spin ordering and chiral spin liquid phases. Ultracold atom systems offer great tunability and flexibility to realize such systems in a wide parameter range of interactions, densities, and spin-imbalance.
In this talk, I will present our recent results on site-resolved imaging of ultracold fermionic lithium atoms on a triangular optical lattice.
Degenerate Fermi gases with about one tenth of the Fermi temperature have been realized within a crossed dipole trap and successfully loaded into a two-dimensional triangular optical lattice. To characterize this lattice, we observed Kapitza-Dirac scattering using a molecular Bose-Einstein condensate. Collecting the emitted photons during Raman sideband cooling in the triangular lattice using a high-resolution microscope objective enabled the high-fidelity imaging of individual fermionic atoms in the lattice with single-site resolution.
The next step will be the realization of a triangular lattice Hubbard model by implementing an additional optical lattice to increase interactions.
This novel experimental platform will allow us to study spin and density correlations in the triangular Hubbard model to explore signatures of frustration and spin-hole bound states and may lead to a direct observation of non-vanishing chiral correlations.
https://web.phys.virginia.edu/Private/Covid-19/colloquium.asp
Friday, October 23, 2020
3:30 PM
Online, Room via Zoom
Note special room.
"Bosonic Quantum Information Processing with Superconducting Circuits"
Professor Liang Jiang , Pritzker School of Molecular Engineering, University of Chicago
[Host: Olivier Pfister]
Bosonic modes are widely used for quantum communication and information processing. Recent developments in superconducting circuits enable us to control bosonic microwave cavity modes and implement arbitrary operations allowed by quantum mechanics, such as quantum error correction against excitation loss errors. We investigate different bosonic encoding and error correction protocols, and provide a perspective on using bosonic quantum error correction for various applications.
https://web.phys.virginia.edu/Private/Covid-19/colloquium.asp
Friday, October 2, 2020
3:30 PM
online, Room via Zoom
Note special room.
"Isolated Superfluid Liquid Helium Drops in a Magneto-Gravitational Trap"
Dr. Charles Brown II , University of California, Berkeley
[Host: Bellave Shivaram]
The unique properties of superfluid 4He (low mechanical stiffness, zero viscosity, high structural and chemical purity and extremely low optical loss) may allow the direct pursuit of optomechanics with quantum mechanical oscillators. We have constructed an optomechanical system consisting entirely of a magnetically levitated drop of superfluid 4He in vacuum. Levitation removes a source of loss associated with physically clamped oscillators. and allows the drop to efficiently cool itself via evaporation. The drop’s optical whispering gallery modes (WGMs) and its surface vibrations couple to each other via the usual optomechanical interactions. We demonstrate the stable magnetic levitation of superfluid 4He drops in vacuum, and present measurements of the drops' evaporation rates, temperatures, optical modes and surface vibrations. We found optical modes with finesse ≈40 (limited by the drop's size). We found surface vibrations with decay rates ∼1
Hz (in rough agreement with theory). Lastly, we found that the drops reach a temperature T≈330
mK, and that a single drop can be trapped indefinitely.
https://web.phys.virginia.edu/Private/Covid-19/colloquium.asp
Friday, September 25, 2020
3:30 PM
Online, Room via Zoom
Note special room.
"Finding Needles in an Avalanche of Haystacks: The New Precision Timing Detector for CMS "
Chris Neu , University of Virginia - Department of Physics
[Host: Bob Jones]
The full potential of the Large Hadron Collider will ultimately be realized through the running period that will take collider operations into the late 2030s. The so-called High Luminosity era of the LHC (HL-LHC), planned to begin in 2027, will see up to a 5-fold increase in the nominal brightness of the LHC beams, which will consequently allow experiments to collect a data set of proton-proton collisions approximately 20 times larger than what has been collected so far in high-energy LHC running. This significant increase in data sample will be a boon for the physics program of the LHC experiments, furthering searches for ultra-rare phenomena and refining precision measurements of known processes. At the CMS experiment, a suite of novel upgrades will be deployed that will enable the experiment to cope with the onslaught of collisions in the high luminosity environment and fully capitalize on the opportunities presented in the HL-LHC era. In this talk I will focus on the MIP Timing Detector (MTD), a device capable of measuring the time-of-arrival for minimum-ionizing particles (MIPs) produced within CMS with a resolution of 30 picoseconds. This entirely new detector system will be built in part at UVA before being shipped to CERN and integrated with the CMS experiment. I will describe the principle of operation of the MTD, the current status of the project and UVA's role in the construction of the device. I will also discuss the expected impact the MTD will have on several high-profile physics signatures that are prime targets in the HL-LHC era and, in particular, the power of using timing information in the reconstruction of exotic long-lived particle decays.
https://web.phys.virginia.edu/Private/Covid-19/colloquium.asp
Friday, September 18, 2020
3:30 PM
Online, Room via Zoom
Note special room.
"Multiscale modeling of metal-insulator transition in correlated electron systems"
Gia-Wei Chern , University of Virginia - Department of Physics
[Host: Bob Jones]
In this talk, I will present our recent efforts on dynamical simulations of correlated electron systems. I will first discuss new quantum molecular dynamics (QMD) methods based on advanced many-body techniques, such as Gutzwiller/slave-boson and dynamical mean-field theory, that are capable of modeling strong electron correlation phenomena. We apply our new QMD to simulate the correlation-induced Mott transition in a metallic liquid, and the nucleation-and-growth of Mott droplets in Hubbard-type models. I will also discuss the implementation of the ab initio Gutzwiller MD for simulating hydrogen liquids under high pressure. To overcome the obstacle of huge computational complexity in such large-scale simulations, I will discuss how simulation efficiency can be significantly improved with the aid of modern machine learning methods. In particular, deep-learning neural-network holds the potential of achieving large-scale quantum-accuracy simulation of correlated systems without the electrons.
https://virginia.zoom.us/j/99745389785
Meeting ID: 997 4538 9785 Passcode: 540373
Friday, September 4, 2020
3:30 PM
online, Room via Zoom
Note special room.
"Programmable Quantum Simulation with Superconducting Qubits and Microwave Photons "
Professor Steven M. Girvin , Department of Physics and Yale Quantum Institute Yale University
[Host: Olivier Pfister and Israel Klich]
‘Circuit QED’ is the quantum theory of superconducting qubits strongly interacting with microwave photons in electrical circuits. It is the leading solid-state architecture in the race to develop large-scale fault-tolerant quantum computers, and is the only technology that has demonstrated quantum error correction that actually extends the lifetime of quantum information.
In this talk, I will present an elementary introduction to the basic concepts underlying superconducting quantum processors. Their ability to control and make quantum non-demolition (QND) measurements of individual microwave photons is a powerful resource for quantum computation, communication and simulation. I will illustrate these capabilities with recent experiments on a programmable quantum simulator that uses efficient boson sampling of microwave photons to predict the Franck-Condon vibrational spectra of various small tri-atomic molecules. Finally, I will briefly explore possible future directions for simulation of quantum many-body problems involving interacting bosons.
Monday, February 24, 2020
3:30 PM
Physics Building, Room 203
Note special date.
Note special room.
"Integrated x(2) photonics"
Professor Hong Tang , Department of Electrical Engineering, Yale University
[Host: UVA Student Chapter of OSA/SPIE]
The ability to generate and manipulate photons with high efficiency and coherence is of critical importance for both fundamental quantum optics studies and practical device applications. However mainstream integrated photonic platforms such as those based on silicon and silicon nitride lack the preferred cubic c(2) nonlinearity, which limits active photon control functionalities. In this talk, I will present integrated photonics based on aluminum nitride (AlN) and lithium niobite (LN), whose non-centrosymmetric crystal structures give rise to the strong second-order optical nonlinearity. Together with their low optical loss, the integrated AlN and LN photonics can provide enhanced c(2) photon-photon interactions to achieve high fidelity photon control, including on-chip parametric down-conversion, coherent light conversion, spectral-temporal shaping, and microwave-to-optical frequency conversions.
Wednesday, February 19, 2020
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
The general lore, according to effective field theory, is that one ignores the high energy degrees of freedom when studying low energy phenomena. For example, we usually do not need to know quantum chromodynamics (QCD) (the strong nuclear force) in order to study fluid mechanics! However, the existence of 't Hooft anomalies (subtle phases in the partition function) may signal non-trivial intertwining between the high and low energy scales. This assertion can be seen in axion physics; axion is a hypothetical particle that may play important roles in solving a few puzzles in the Universe. After a brief introduction to QCD and axions, I show how this intertwining takes place on axion domain walls (DW). To this end, I first discuss a new class of 't Hooft anomalies that was recently identified, and then use the anomalies to argue that quarks are deconfined (liberated) on axion DW. This newly discovered phenomenon implies that non-trivial interplay between different scales happens on the walls. Further, I confirm this picture by performing explicit calculations in a toy model, which is argued to be continuously connected to the full-fledged QCD.
Wednesday, February 12, 2020
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
"New connections between Quantum Field Theory and String Theory"
Christoph Uhlemann , University of Michigan
[Host: Peter Arnold]
Quantum field theory is a universal language in theoretical physics, which provides the foundation for the Standard Model of elementary particles, underlies the physics of the early universe, and describes a wealth of interesting phenomena in condensed matter. But despite its great successes, fully understanding this important framework is still very much a work in progress. Many insights, especially into theories with strong interactions, have been obtained using mathematical tools from string theory, and this has reshaped our understanding of what quantum field theory is. In this talk I will discuss new connections between quantum field theory and string theory that provide access to a remarkable class of theories that would not have been believed to exist based on conventional lore.
Wednesday, February 5, 2020
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
"Neutrinos - Harbingers of New Physics"
Julian Heeck , University of California, Irvine
[Host: Peter Arnold]
Neutrinos are the most elusive known elementary particles; they fly through all of us in vast numbers but are extremely difficult to detect. Immense progress has been made in analyzing their properties over the last decades, culminating in the surprising discovery of neutrino flavor oscillations. These neutrino oscillations imply that neutrinos have tiny but nonzero masses, which provides strong evidence for physics beyond the Standard Model of particle physics. With the increasing precision in neutrino measurements it has even become possible to use neutrinos as a tool to probe for further new physics, e.g. by studying how neutrinos scatter off electrons. In addition, neutrinos could prove uniquely helpful in the search for dark matter and provide complementary information to standard indirect detection signatures.
Wednesday, January 29, 2020
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
"Generating New Physics from Known Particles: Baryogenesis and Dark Matter from Mesons"
Gilly Elor , University of Washington
[Host: Peter Arnold]
I will address two of the most fundamental questions about our Universe -- "What is the Universe made of?” and "How did complex structures come to exist?”. These translate into understanding the origins of dark matter and a mechanism to generate the asymmetry of matter over anti-matter in the early Universe. I will put these problems in context and then present a novel, testable, solution to both mysteries in the same framework. The key idea is to rely on Standard Model particles called Beauty (B) Mesons which decay into dark matter particles. This mechanism has multiple testable signals. Some experimental searches are already under development, the results of which could yield the first hints of how nature chose to address these profound questions.
Friday, January 24, 2020
3:30 PM
Physics Building, Room 204
Note special room.
"What do we learn about gravity & nuclear physics from gravitational waves?"
Kent Yagi , University of Virginia - Department of Physics
[Host: Bob Jones]
A hundred years after the prediction by Einstein, gravitational waves were directly detected for the first time in 2015 by LIGO, which marked the dawn of gravitational-wave astronomy. Gravitational waves are sourced by astrophysical compact objects, such as black holes and neutron stars. Due to their extremely large gravitational field and compactness, they offer us natural testbeds to probe strong-field gravity and dense matter physics. In this talk, I first give an overview of the current status of gravitational-wave observations. Next, I explain how well one can test General Relativity, constrain the equation of state of nuclear matter and measure nuclear parameters with gravitational waves. I also comment on how one can combine gravitational-wave information with the recent measurement of a neutron star radius by an X-ray payload NICER to further probe nuclear physics.
Wednesday, January 22, 2020
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
When learning about the properties of a quantum mechanical system, for instance, the energy levels of its bound states, it is useful to think of the system as closed and isolated from any environment, though we know in any laboratory setting, all systems eventually will interact with an environment. However, we can often engineer such interactions to be weak, short-ranged, and controllable, so that the isolated approximation is a good one.
I will argue that in many physically relevant field theories, the long-time observables or states of the theory can only be defined in the context of a quantum open system, where we take into account the interactions between the system and the environment continually in the evolution of the system. This is because excitations of the field theory will inevitably create their own environment, that is, states we must trace over. Resumming these interactions with the self-created environment is necessary to give a convergent expansion for observables over all of phase-space.
Wednesday, January 15, 2020
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
"The holographic view on transport in strongly interacting plasmas"
Saso Grozdanov , MIT
[Host: Peter Arnold]
Microscopic quantum interactions between elementary particles control transport in macroscopic states of matter, such as in fluids and plasmas. In numerous states of interest, these microscopic interactions are strong, including in water, among electrons in graphene and in quark-gluon plasma — a state of nuclear matter that filled the early Universe and that is currently being recreated in particle colliders. While macroscopic theories describing the dynamics of such states, in particular, hydrodynamics (of fluids) and magnetohydrodynamics (of magnetized plasmas) have been partially understood, a full description of transport also requires a certain microscopic knowledge of its underlying quantum physics. After more than a century of striking advance in quantum theories, our theoretical understanding of these microscopic processes remains mostly limited to states with weak interactions. Recently, however, string theory also enabled explorations of strongly interacting states through the mathematical statement of holographic duality, which translates otherwise intractable problems into simpler analyses of black holes and gravitational waves.
In my talk, I will first discuss new aspects of the macroscopic theory of hydrodynamics, focusing on the properties of the infinite series of higher-order corrections to the infamous Navier-Stokes equations. By using a novel concept of generalized global symmetries, which can encode the fact that the number of magnetic flux lines in Nature is conserved, I will then describe the construction of a new, comprehensive theory of magnetohydrodynamics. This reformulation has led to a number of general theoretical and experimental predictions for transport in magnetized plasmas. I will then move on to discuss the microscopic physics responsible for transport in strongly interacting states. Beginning with an introduction of holographic duality, this section will summarize holographic insights into the problem of the “unreasonable effectiveness of hydrodynamics” for the description of quark-gluon plasma. Then, I will discuss how the descriptions of microscopic physics and transport transition between strongly and weakly interacting pictures. Finally, by utilizing the mathematical structure behind our new theory of magnetohydrodynamics, a holographic dual of magnetized plasmas will be presented along with the first analyses of strongly interacting magnetized transport.
Friday, December 6, 2019
3:30 PM
Physics Building, Room 204
Note special room.
"Exploring the Nucleon Sea"
Jen-Chieh Peng , University of Illinois at Urbana-Champaign
[Host: Simonetta Liuti]
Direct experimental evidence for point-like constituents in the nucleons
was first found in the electron deep inelastic scattering (DIS) experiment.
The discovery of the valence and sea quark structures in the nucleons
inspired the formulation of Quantum Chromodynamics (QCD) as the gauge field
theory governing the strong interaction. A surprisingly large asymmetry
between the up and down sea quark distributions in the nucleon was observed
in DIS and the so-called Drell-Yan experiments. In this talk, I discuss the
current status of our knowledge on the flavor structure of the nucleon sea.
I will also discuss the progress in identifying the "intrinsic" sea
components in the nucleons. Future prospect for detecting some novel
sea-quark distributions will also be presented.
Friday, November 15, 2019
3:30 PM
Physics Building, Room 203
Note special room.
"Multimessenger astronomy of compact binaries from the vantage point of computational gravity"
Prof. Vasileios Paschalidis , University of Arizona
[Host: Kent Yagi]
We live in an exciting era where strong-field gravity has become a central pillar in the study of astrophysical sources. For the first time in history the detection of gravitational waves and simultaneous electromagnetic signals (multimessenger astronomy) from the same source have the potential to solve some of the most long-standing problems in fundamental physics and astrophysics. Computational gravity plays an important role in the success of the multimessenger astronomy program. Using the vantage point of computational gravity, in this talk we will we focus on how observations of colliding neutron stars can teach us about the state of matter at densities greater than the nuclear density, and with a critical eye assess what we have learnt so far from the first observation of a binary neutron star (event GW170817). We will also discuss how multimessenger detection of collisions of binary black holes may inform us about their environments andthe nature of black holes.
Friday, November 8, 2019
3:30 PM
Physics Building, Room 204
Note special room.
"Testing Einstein with numerical relativity: theories beyond general relativity, and the precision frontier"
Professor Leo Stein , University of Mississippi
[Host: Kent Yagi]
Advanced LIGO and Virgo have already detected black holes crashing into each other at least ten times. With their upgrades we anticipate a rate of about 1 gravitational-wave detection per week. More signals and higher precision will take the dream of testing Einstein's theory of gravity, general relativity, and make it a reality. But would we know a correction to Einstein's theory if we saw it? How do we make predictions from theories beyond GR? And do current numerical relativity simulations have enough precision that we could be confident in any potential discrepancy between observations and predictions? I will discuss (i) how to perform simulations in beyond-GR theories of gravity, and (ii) how numerical relativity simulations need to improve to be ready for the precision frontier of gravitational wave astrophysics.
Friday, November 1, 2019
3:30 PM
Physics Building, Room 204
Note special room.
"Studying the stars here on earth: Experimental investigations of the nuclear equation-of-state "
Sherry Yennello , Texas A&M University
[Host: Simonetta Liuti]
Heavy-ion collisions can produce nuclear material over a range of densities and proton fractions to study the nuclear equation-of-state. These measurements are enabled by accelerating nuclei to – in some cases – GeV energies and detecting the fragments that are produced from the collisions. The detectors are multi-detector arrays capable of measuring dozens of particles simultaneously from a single collision. Data rates can range up to many hundreds of collisions per second. One can either explore the characteristics of the individual fragments that are produced, often extracting particle ratios or double ratios, or correlations between the fragments – in particular transverse collective flow. From very low density to about three times normal nuclear density measurements have been made of the density dependence of the asymmetry energy. I will present an overview of how these measurements have been made and the constraints they have set on the nuclear equation-of-state.
"Phase space characterization of optical quantum states and quantum detectors"
Rajveer Nehra , University of Virginia - Physics
We are in the midst of a second quantum revolution fueled by “quantumness” of physical systems and the sophisticated measurement devices or detectors to produce and characterize these exotic systems. Thus, characterization of quantum states and the detectors is a key task in optical quantum science and technology. The Wigner quasi-probability distribution function provides such a characterization. In this talk, I present our recent results on quantum state tomography of a single-photon Fock state using photon-number-resolving measurements using superconducting transition-edge sensor [1]. We directly probe the negativity of the Wigner function in our raw data without any inference or correction for decoherence, which is also an important indicator of the “quantum-only” nature of a physical system. For the second part of the talk, we discuss a method to characterize quantum detectors by experimentally identifying the Wigner functions of the detector positive-operator-value-measures (POVMs), a set of hermitian operators completely describing the detector [2]. The proposed scheme uses readily available thermal mixtures and probes the Wigner function point-by-point over the entire phase space from the detector’s outcome statistics. In order to make the reconstruction robust to the experimental noise, we use techniques from convex quadratic optimizations.
References
1. R. Nehra, A. Win, M. Eaton, R. Shahrokhshahi, N. Sridhar, T. Gerrits,A. Lita, S. W. Nam, and O. Pfister, “State-independent quantum state tomography by photon-number-resolving measurements,” Optica 6,1356–1360 (2019). 2. R. Nehra and K. Valson Jacob (2019), “Characterizing quantum detectors by Wigner functions,” [arXiv:1909.10628].
"Ferroelectric Polarons, Belgian Waffles, and Principles for “Perfect” Semiconductors"
Professor Xiaoyang Zhu , Columbia University
[Host: Seunghun Lee]
Lead halide perovskites have been demonstrated as high performance materials in solar cells and light-emitting devices. These materials are characterized by coherent band transport expected from crystalline semiconductors, but dielectric responses and phonon dynamics typical of liquids. Here we explain the essential physics in this class of materials based on their dielectric functions and dynamic symmetry breaking on nano scales. We show that the dielectric function in the THz region may lead to dynamic and local ordering of polar nano domains by an extra electron or hole, resulting a quasiparticle which we call a ferroelectric large polaron, a concept similar to solvation in chemistry. Compared to a conventional large polaron, the collective nature of polarization in a ferroelectric large polaron may give rise to order(s)-of-magnitude larger reduction in the Coulomb potential. We show that the shape of a ferroelectric polaron resemble that of a Belgian waffle. Using two-dimensional coherent phonon spectroscopy, we directly probe the energetics and local phonon responses of the ferroelectric large polarons. We find that that electric field from a nascent e-h pair drives the local transition to a hidden ferroelectric order on picosecond time scale. The ferroelectric or Belgian waffle polarons may explain the defect tolerance and low recombination rates of charge carriers in lead halide perovskites, as well as providing a design principle of the “perfect” semiconductor for optoelectronics.
Friday, September 13, 2019
3:30 PM
Physics Building, Room 204
Note special room.
"Quantum states, walks, tiles, and tensor networks"
Israel Klich , University of Virginia - Physics
[Host: Bob Jones]
A major challenge of physics is the complexity of many-body systems. While true for classical systems, the difficulty is exasperated in quantum systems, due to entanglement between system components and thus the need to keep track of an exponentially large number of parameters. In particular, this complexity places a challenge to numerical methods such as quantum Monte Carlo and tensor networks. Here, exactly solvable models are of crucial importance: we use these to test numerical procedures, to develop intuition, and as a starting point for approximations.
In this talk, I will explain our current understanding of a new solvable "walk" model, the area deformed Motzkin model. The model shows that entanglement may be more acute than previously thought, in particular, it features a novel quantum phase transition between a non-entangled phase and extensively entangled “rainbow” phase. Most remarkably, the model motivated the construction of a new tensor network, providing, after many years, the first example for an exact tensor network description of a critical system. Finally, I will remark on open problems, and on exciting connections to other fields such as the notion of holography in field theory, and a famous problem in non-equilibrium statistical mechanics.
Friday, September 6, 2019
2:30 PM
Physics Building, Room 204
Note special time.
Note special room.
"Neutron stars droplets and the quarks within"
Professor Or Hen , MIT - Massachusetts Institute of Technology
[Host: Nilanga Liyanage]
Neutron stars are one of the densest strongly-interacting many-body systems in our universe. A main challenge in describing the structure and dynamics of neutron stars steams from our limited understanding of the nuclear interaction at high-densities (i.e. short-distances) and its relation to the underlaying quark-gluon substructure of nuclei.
In this talk I will present new results from high-energy electron scattering experiments that probe the short-ranged part of the nuclear interaction via the hard breakup of Short-Range Correlations (SRC) nucleon pairs. As the latter reach densities comparable to those existing in the outer core of neutron stars, they represent ’neutron stars droplets’ who’s study can shed new light to the dynamical structure of neutron stars. Special emphasis will be given to the effect of SRCs to the behavior of protons in neutron-rich nuclear systems and how it can impact the cooling rates and equation of state of neutron stars. Pursuing a more fundamental understanding of such interactions, I will present new measurements of the internal quark-gluon sub-structure of nucleons and show how its modification in the nuclear medium relates to SRC pairs and short-ranged nuclear interactions.
Given time I will also discuss the development of new effective theories for describing short-ranged correlations, the way in which they relate to experimental observables, and the emerging universality of short-distance and high-momentum physics in nuclear systems.
Friday, August 30, 2019
3:30 PM
Physics Building, Room 204
Note special room.
"From interacting Majorana to universal fractional quasiparticles"
Jeffrey Teo , University of Virginia - Physics
[Host: Bob Jones]
Ising anyons, Majorana fermions (MF) and zero energy Majorana bound states have promising prospects in topological quantum computing (TQC) because of their ability to store quantum states non-locally in space and insensitivity to local decoherence. Unfortunately, these objects are not powerful enough to assemble a TQC that can perform universal operations using topological braiding operations alone. On the other hand, there are anyonic quasiparticles, like the Fibonacci anyon in a Read-Rezayi quantum Hall state, that are universal in the braiding-based TQC sense. However, these are quantum dynamical excitations, which can be challenging to spatially manipulate and susceptible to temperature fluctuations in a thermodynamic system. We propose and define a new notion of universal fractional quasiparticles, which are semi-classical static topological defects, supported by many-body interacting MFs in a superconducting spin-orbit coupled topological electronic system.
Friday, April 26, 2019
3:30 PM
Physics Building, Room 204
Note special room.
"From Multimessenger Astronomy to Neutrons and Protons"
Andrew Steiner , University of Tennessee
[Host: Kent Yagi]
Of course, multimessenger astronomy promises to revolutionize
astronomy and our understanding of nucleosynthesis. My
research shows that it goes further: astronomical observations
(via both photons and gravitational waves) provides a unique
laboratory to deepen our understanding of QCD and the
nucleon-nucleon interaction. Most current work is focused
on the equation of state. While the equation of state is
indeed important, in this talk, I show how we can
go beyond energy density and pressure. I present the first
large-scale Bayesian inference of neutron star observations
and nuclear structure data to obtain novel results on the
composition of dense matter and the nature of nucleonic
superfluidity.
Friday, April 19, 2019
3:30 PM
Physics Building, Room 204
Note special room.
"Emergence of Mass in the Standard Model"
Dr. Craig D. Roberts , Argonne National Laboratory
[Host: Nilanga Liyanage]
Quantum Chromodynamics (QCD), the nuclear physics part of the Standard Model, is the first theory to demand that science fully resolve the conflicts generated by joining relativity and quantum mechanics. Hence in attempting to match QCD with Nature, it is necessary to confront the innumerable complexities of strong, nonlinear dynamics in relativistic quantum field theory. The peculiarities of QCD ensure that it is also the only known fundamental theory with the capacity to sustain massless elementary degrees-of-freedom, gluons (gauge bosons) and quarks (matter fields); and yet gluons and quarks are predicted to acquire mass dynamically so that the only massless systems in QCD are its composite Nambu-Goldstone bosons. All other everyday bound states possess nuclear-size masses, far in excess of anything that can directly be tied to the Higgs boson. These points highlight the most important unsolved questions within the Standard Model, namely: what is the source of the mass for the vast bulk of visible matter in the Universe and how is this mass distributed within hadrons? This presentation will provide a contemporary sketch of the strong-QCD landscape and insights that may help in answering these questions.
Friday, April 12, 2019
3:30 PM
Physics Building, Room 204
Note special room.
"Computing Images from Weak Optical Signals"
Dr. Vivek Goyal , Boston University
[Host: MIller Eaton]
In conventional imaging systems, the results are poor unless there is a physical mechanism for producing a sharp image with high signal-to-noise ratio. In this talk, I will present two settings where computational methods enable imaging from very weak signals: range imaging and non-line-of-sight (NLOS) imaging.
Lidar systems use single-photon detectors to enable long-range reflectivity and depth imaging. By exploiting an inhomogeneous Poisson process observation model and the typical structure of natural scenes, first-photon imaging demonstrates the possibility of accurate lidar with only 1 detected photon per pixel, where half of the detections are due to (uninformative) ambient light. I will explain the simple ideas behind first-photon imaging and lightly touch upon related subsequent works that mitigate the limitations of detector arrays, withstand 25-times more ambient light, allow for unknown ambient light levels, and capture multiple depths per pixel.
NLOS imaging has been an active research area for almost a decade, and remarkable results have been achieved with pulsed lasers and single-photon detectors. Our work shows that NLOS imaging is possible using only an ordinary digital camera. When light reaches a matte wall, it is scattered in all directions. Thus, to use a matte wall as if it were a mirror requires some mechanism for regaining the one-to-one spatial correspondences lost from the scattering. Our method is based on the separation of light paths created by occlusions and results in relatively simple computational algorithms.
Related paper DOIs:
10.1126/science.1246775
10.1109/TSP.2015.2453093
10.1109/LSP.2015.2475274
10.1364/OE.24.001873
10.1038/ncomms12046
10.1109/TSP.2017.2706028
10.1038/s41586-018-0868-6
Friday, March 29, 2019
3:30 PM
Physics Building, Room 204
Note special room.
"Interfaces in oxide quantum heterostructures"
Dr. Ho Nyung Lee , Oak Ridge National Laboratory
[Host: Seunghun Lee]
Complex oxides are known to possess the full spectrum of fascinating properties, including magnetism, colossal magneto-resistance, superconductivity, ferroelectricity, pyroelectricity, piezoelectricity, multiferroicity, ionic conductivity, and more. This breadth of remarkable properties is the consequence of strong coupling between charge, spin, orbital, and lattice symmetry. Spurred by recent advances in the synthesis of such artificial materials at the atomic scale, the physics of oxide heterostructures containing atomically smooth layers of such correlated electron materials with abrupt interfaces is a rapidly growing area. Thus, we have established a growth technique to control complex oxides at the level of unit cell thickness by pulsed laser epitaxy. The atomic-scale growth control enables to assemble the building blocks to a functional system in a programmable manner, yielding many intriguing physical properties that cannot be found in bulk counterparts. In this talk, examples of artificially designed, functional oxide heterostructures will be presented, highlighting the importance of heterostructuring, interfacing, and straining. The main topics include (1) charge transfer induced interfacial magnetism and topologically non-trivial spin textures in SrIrO3-based heterostructures and (2) lattice and chemical potential control of oxygen stability and associated electronic and magnetic properties in nickelate-and cobaltite-based heterostructures.
This work was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division.
Friday, March 22, 2019
3:30 PM
Physics Building, Room 204
Note special room.
"A Mathematical Journey Thru SUSY, Error-Correcting Codes, Evolution, and a Sustainable Reality "
Jim Gates, Ph.D. , Brown University
[Host: Diana Vaman]
This presentation describes an arc in mathematical/theoretical physics traversing concepts from equations, graphs, error-correction, and pointing toward an evolution-like process acting on the mathematical laws that sustain reality.
Friday, March 1, 2019
3:30 PM
Physics Building, Room 204
Note special room.
"Kelvin-Froude wake patterns of a traveling pressure disturbance"
Genya Kolomeisky , University of Virginia - Physics
[Host: Israel Klich]
Water wave patterns behind ships fuel human curiosity because they are both beautiful and easily observed. These patterns called wakes were famously described in 1887 by Lord Kelvin. According to Kelvin, the feather-like appearance of the wake is universal and the entire wake is confined within a 39 degree angle. While such wakes have been observed, deviations from Kelvin’s predictions have also been reported. In this talk summarizing my work with UVA alumnus Jonathan Colen I will present a quantitative reasoning based on classical surface water wave theory that explains why some wakes are similar to Kelvin’s prediction, and why others are less so. The central result is a classification of wake patterns which all can be understood in terms of the problem originally treated by Kelvin.
Wednesday, February 20, 2019
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
"Gravitational waves and fundamental properties of matter and spacetime"
David Nichols , University of Amsterdam
[Host: Diana Vaman]
Gravitational waves from the mergers of ten binary black holes and one binary neutron star were detected in the first two observing runs by the Advanced LIGO and Virgo detectors. In this talk, I will discuss the eleven gravitational-wave detections and the electromagnetic observations that accompanied the neutron-star merger. These detections confirmed many of the predictions of general relativity, and they initiated the observational study of strongly curved, dynamical spacetimes and their highly luminous gravitational waves. One aspect of these high gravitational-wave luminosities that LIGO and Virgo will be able to measure is the gravitational-wave memory effect: a lasting change in the gravitational-wave strain produced by energy radiated in gravitational waves. I will describe how this effect is related to symmetries and conserved quantities of spacetime, how the memory effect can be measured with LIGO and Virgo, and how new types of memory effects have been recently predicted. I will conclude by discussing the plans for the next generation of gravitational-wave detectors after LIGO and Virgo and the scientific capabilities of these new detectors. These facilities could detect millions of black-hole and neutron-star mergers per year, and they can provide insights on a range of topics from the population of short gamma-ray bursts to the presence of dark matter around black holes.
Wednesday, February 13, 2019
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
"Frontiers in Multi-Messenger Astrophysics at the interface of gravitational wave astrophysics, large scale astronomical surveys and data science "
Eliu Huerta , University of Illinois at Urbana-Champaign
[Host: Diana Vaman]
The next decade promises fundamental new scientific insights and discoveries from Multi-Messenger Astrophysics, enabled through the convergence of large scale astronomical surveys, gravitational wave astrophysics, deep learning and large scale computing. In this talk I describe a Multi-Messenger Astrophysics science program, and highlight recent accomplishments at the interface of gravitational wave astrophysics, numerical relativity and deep learning. I discuss the convergence of this program with large scale astronomical surveys in the context of gravitational wave cosmology. Future research and development activities are discussed, including a vision to leverage data science initiatives at the University of Virginia to spearhead, maximize and accelerate discovery in the nascent field of Multi-Messenger Astrophysics.
Wednesday, February 6, 2019
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
Black holes are bridges between astrophysics and fundamental physics. I will describe three examples of this theme. First, I will explain how contemporary theoretical ideas deriving from the holographic principle have proven useful for interpreting numerical simulations of electromagnetic outflows from spinning black holes. These models are currently being tested against X-ray and radio observations of galactic black holes. Second, I will describe a correspondence between black holes and lower dimensional fluids and discuss the possibility of probing this correspondence with gravitational wave memory experiments. Finally, I will describe how gravitational wave observations of black hole tidal interactions might be used to find new symmetries acting on the event horizon.
Wednesday, January 30, 2019
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
"Testing Gravity with Cosmology and Astrophysics"
Jeremy Sakstein , University of Pennsylvania
[Host: Diana Vaman]
We are entering a golden age of cosmology and astrophysics. In the coming decade we will have cosmological data for over a billion galaxies, a census of objects in the Milky Way, and a network of gravitational detectors spanning the globe that will detect thousands of events per year. This presents us with the unprecedented opportunity to learn how gravity behaves at the largest distances, and in the most extreme environments. In this talk I will describe how we can use current and upcoming data to understand the unexplained mysteries of the Universe, such as why the expansion of the Universe accelerating (dark energy). I will also discuss how to connect physics in these disparate regimes and how to test cosmology on small scales. To maximize the discovery potential of the data requires us to construct robust theoretical models, identify novel probes, and connect theory with observation, and I will describe projects where I have attempted to accomplish this. I will conclude the talk by discussing how this interdisciplinary effort will continue into the next decade and beyond.
Wednesday, January 23, 2019
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
"Probing Massive and Supermassive Black Holes with Gravitational Waves"
Sarah Vigeland , University of Wisconsin Milwaukee
[Host: Diana Vaman]
Observations have shown that nearly all galaxies harbor massive or supermassive black holes at their centers. Gravitational wave (GW) observations of these black holes will shed light on their growth and evolution, and the merger histories of galaxies. Massive and supermassive black holes are also ideal laboratories for studying strong-field gravity. Pulsar timing arrays (PTAs) are sensitive to GWs with frequencies ~1-100 nHz, and can detect GWs emitted by supermassive black hole binaries, which form when two galaxies merge. The Laser Interferometer Space Antenna (LISA) is a planned space-based GW detector that will be sensitive to GWs ~1-100 mHz, and it will see a variety of sources, including merging massive black hole binaries and extreme mass-ratio inspires (EMRIs), which consist of a small compact object falling into a massive black hole. I will discuss source modeling and detection techniques for LISA and PTAs, as well as present limits on nanohertz GWs from the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) collaboration.
Friday, January 18, 2019
3:30 PM
Physics Building, Room 204
Note special room.
Quantum Chromodynamics (QCD), the theory of the strong interaction, is a cornerstone of the Standard Model of modern physics. It explains all nuclear matter as bound states of point-like fermions, known as quarks, and gauge bosons, known as gluons. The gluons bind not only quarks but also interact with themselves. Unlike with the more familiar atomic and molecular matter, the interactions and structures are inextricably mixed up, and the observed properties of nucleons and nuclei, such as mass and spin, emerge out of this complex system. To precisely image the quarks and gluons and their interactions and to explore the new QCD frontier of strong color fields in nuclei, the Nuclear Physics community proposes an US-based Electron Ion collider (EIC) with high-energy and high-luminosity, capable of a versatile range of beam energies, polarizations, and ion species. The community is convinced that the EIC is the right tool to understand how matter at its most fundamental level is made.
Thursday, January 17, 2019
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
"Quantum Engineering: A Transdisciplinary Vision"
Prem Kumar , Northwestern University
[Host: Bob Jones]
A global quantum revolution is currently underway based on the recognition that the subtler aspects of quantum physics known as superposition (wave-like aspect), measurement (particle-like aspect), and entanglement (inseparable link between the two aspects) are far from being merely intriguing curiosities, but can be transitioned into valuable, real-world technologies with performances that can far exceed those obtainable with classical technologies. The recent demonstration by the Chinese scientists of using a low-earth-orbit satellite to distribute entangled photons to two ground stations that are over a thousand kilometers apart is a stunning technological achievement—direct entanglement distribution over the best available fiber links is limited to a few hundred kilometers—and a harbinger of future possibilities for globally secure communications guaranteed by the power of quantum physics.
Harnessing the advantages enabled by superposition, measurement, and entanglement (SME)—the three pillars of quantum physics—for any given application is what is termed quantum engineering in general. In many instances, however, the details of the underlying science (high-temperature superconductivity, photosynthesis, avian navigation, are some examples) is still not fully understood, let alone how to turn the partially understood science into a potentially useful technology. Nevertheless, it has become clear in the last few decades that quantum engineering will require a truly concerted effort that will need to transcend the traditional disciplinary silos in order to create and sustain new breeds of science and technology communities that will be equally versed in quantum physics as they would be in their chosen area of technology. In this talk, I will present my vision for unleashing the potential of quantum engineering, taking some examples from ongoing and proposed research.
Wednesday, January 16, 2019
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
"Frontiers of Multi-Messenger Black-Hole Physics"
Stephen Taylor , California Institute of Technology
[Host: Diana Vaman ]
The bounty of gravitational-wave observations from LIGO and Virgo has opened up a new window onto the warped Universe, as well as a pathway to addressing many of the contemporary challenges of fundamental physics. I will discuss how catalogs of stellar-mass compact object mergers can probe the unknown physical processes of binary stellar evolution, and how these systems can be harnessed as standard distance markers (calibrated entirely by fundamental physics) to map the expansion history of the cosmos. The next gravitational-wave frontier will be opened within 3-6 years by pulsar-timing arrays, which have unique access to black-holes at the billion to ten-billion solar mass scale. The accretionary dynamics of supermassive black-hole binaries should yield several tell-tale signatures observable in upcoming synoptic time-domain surveys, as well as gravitational-wave signatures measurable by pulsar timing. Additionally, pulsar-timing arrays are currently placing compelling constraints on modified gravity theories, cosmic strings, and ultralight scalar-field dark matter. I will review my work on these challenges, as well as in the exciting broader arena of gravitational-wave astrophysics, and describe my vision for the next decade of discovery.
Friday, December 7, 2018
3:30 PM
Physics Building, Room 204
Note special room.
" Using Topology to Solve Strongly Coupled Quantum Field Theories"
Zohar Komargodski , Stony Brook University
[Host: Marija Vucelja]
I will begin by describing an interacting model in Quantum Mechanics where exact results about the ground state can be established by using tools from topology. I will then argue that such tools are also useful for tackling interesting problems in Quantum Field Theory. In particular, I will review Yang-Mills theory and argue that using topology one can make several predictions about its possible phases. We will then also extend the considerations to Quantum Chromodynamics and discuss possible connections with particle physics phenomenology and with condensed matter physics.
Friday, November 30, 2018
3:30 PM
Physics Building, Room 204
Note special room.
"A new approach to search for neutron-antineutron oscillations, and a couple of other phenomena based on neutron reflection from surface: gravitational and whispering-gallery quantum states of neutrons"
Valery Nesvizhevsky , Institut Laue Langevin, France
[Host: Stefan Baessler]
“An observation of neutron-antineutron oscillations (n-n ̅), which violate both B and B — L conservation, would constitute a scientific discovery of fundamental importance to physics and cosmology. A stringent upper bound on its transition rate would make an important contribution to our understanding of the baryon asymmetry of the universe by eliminating the post-sphaleron baryogenesis scenario in the light quark sector. We show that one can design an experiment using slow neutrons that in principle can reach the required sensitivity of 1010 s in the oscillation time, an improvement of 104 in the oscillation probability relative to the existing limit for free neutrons. This can be achieved by allowing both the neutron and antineutron components of the developing superposition state to coherently reflect from mirrors. We present a quantitative analysis of this scenario and show that, for sufficiently small transverse momenta of n/n ̅ and for certain choices of nuclei for the n/n ̅ guide material, the relative phase shift of the n and n ̅ components upon reflection and the n ̅ annihilation rate can be small. While the reflection of n ̅ from surface looks exotic and counterintuitive and seems to contradict to the common sense, in fact it is fully analogous to the reflection of n from surface. The later phenomenon is well known and used in neutron research from its first years. We illustrate it with two selected example of gravitational and whispering-gallery quantum states of neutrons.”
[V.V. Nesvizhevsky, A.Yu. Voronin, Surprising Quantum Bounces, Imperial College Press, London, 2015]
Friday, November 16, 2018
3:30 PM
Physics Building, Room 204
Note special room.
"Energy-efficient neuromorphic computing with magnetic tunnel junctions"
Mark Stiles , NIST
[Host: Joe Poon & Avik Ghosh]
Human brains can solve many problems with orders of magnitude more energy efficiency than traditional computers. As the importance of such problems, like image, voice, and video recognition, increases, so does the drive to develop computers that approach the energy efficiency of the brain. Magnetic devices, especially tunnel junctions, have several properties that make them attractive for such applications. Their conductance depends on the state of the ferromagnets making it easy to read information that is stored in their magnetic state. In addition, current can manipulate the magnetic state. Based on this electrical control of the magnetic state, magnetic tunnel junctions are actively being developed for integration into CMOS integrated circuits to provide non-volatile memory. This development makes it feasible to consider other geometries that have different properties. I describe two of the computing primitives that have been constructed based on the different functionalities of magnetic tunnel junctions. The first of these uses tunnel junctions in their superparamagnetic state as the basis for a population coding scheme. The second uses them as non-linear oscillators in the first nanoscale “reservoir” for reservoir computing.
Friday, November 9, 2018
3:30 PM
Physics Building, Room 204
Note special room.
"Thermal relaxations, the Mpemba effect, and adaptation of bacteria "
Marija Vucelja , UVA-Physics
[Host: Bob Jones]
Most of my talk will be about anomalous thermal relaxations, such as the Mpemba effect. Towards the end of my talk, I will also highlight a few topics in population dynamics that I have been working on.
The Mpemba effect is a phenomenon when "hot can cool faster than cold" - a “shortcut” in relaxation to thermal equilibrium. It occurs when a physical system initially prepared at a hot temperature, cools down faster than an identical system prepared at a colder temperature. The effect was discovered as a peculiarity of water. Despite following observations in granular gasses, magnetic alloys, and spin glasses, the effect is still most often referred to as an “oddity” of water, although it is widespread and general. I will describe how to define a Mpemba effect for an arbitrary physical system, and show how to quantify and estimate the probability of the Mpemba effect on a few examples.
In the remaining time, I will briefly talk about the adaptation of bacterial populations and the immune system of bacteria with CRISPR. Besides being the biology's newest buzzword and favorite gene editing tool, CRISPR is also a mechanism that allows bacteria to defend adaptively against phages and other invading genomic material. From the standpoint of physics and biology, the coevolution of bacteria and phages yields fascinating open questions.
Friday, October 26, 2018
3:30 PM
Physics Building, Room 204
Note special room.
""Building a Quantum Computer Using Silicon Quantum Dots""
Susan Coppersmith , University of Wisconsin - Madison
[Host: Despina Louca]
The steady increase in computational power of information processors over the past half-century has led to smart phones and the internet, changing commerce and our social lives. Up to now, the primary way that computational power has increased is that the electronic components have been made smaller and smaller, but within the next decade feature sizes are expected to reach the fundamental limits imposed by the size of atoms. However, it is possible that further huge increases in computational power could be achieved by building quantum computers, which exploit in new ways of the laws of quantum mechanics that govern the physical world. This talk will discuss the challenges involved in building a large-scale quantum computer as well as progress that we have made in developing a quantum computer using silicon quantum dots. Prospects for further development will also be discussed.
Friday, October 5, 2018
3:30 PM
Physics Building, Room 204
Note special room.
"Unveiling the Normal State of Cuprate High-Temperature Superconductors: Hidden Order of Cooper Pairs"
Dragana Popovic , Florida State University
[Host: Despina Louca]
Many unusual properties of strongly correlated materials have been attributed to the proximity of quantum phase transitions (QPTs), where different types of orders compete and coexist, and may even give rise to novel phases. In two-dimensional (2D) systems, the nature of the magnetic-field-tuned QPT from a superconducting to a normal state has been widely studied, but it remains an open question. Underdoped copper-oxide high-temperature superconductors are effectively 2D materials and thus present a promising new platform for exploring this long-standing problem. Although in cuprates the normal state is commonly probed by applying a perpendicular magnetic field (H) to suppress superconductivity, the identification and understanding of the H-induced normal state has been a challenge because of the complex interplay of disorder, temperature and quantum fluctuations, and the near-universal existence of charge-density-wave correlations.
This talk will describe recent experimental advances in identifying and characterizing a full sequence of ground states as a function of H in underdoped cuprates. In both the absence and the presence of charge order, the results demonstrate the key role of disorder in the H-tuned suppression of 2D superconductivity, giving rise to an intermediate regime with large quantum phase fluctuations, in contrast to the conventional scenario. Most strikingly, the interplay of the “striped” charge order with high-temperature superconductivity leads to the emergence of an unanticipated, insulatinglike ground state with strong superconducting phase fluctuations, suggesting an unprecedented freezing (i.e. “the hidden order”) of Cooper pairs. Possible scenarios will be discussed, including the implications of the results for understanding the physics of the cuprate pseudogap regime, as well as other 2D superconductors.
Thursday, October 4, 2018
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
"Charge density wave phase transitions in transition metal dichalcogenides"
Utpal Chatterjee , University of Virginia - Department of Physics
[Host: Bob Jones]
Layered transition-metal dichalcogenides (TMDs) are well known for their rich phase diagrams, which
encompass diverse quantum states including metals, semiconductors, Mott insulators, superconductors, and
charge density waves (CDWs). For instance, 2H-NbSe2 and 2H-TaS2 are canonical incommensurate CDW
systems, while 1T-TiSe2 harbors a commensurate CDW order. There is a coexistence/competition of CDW
and superconductivity in 2H-NbSe2 and 2H-TaS2, though this is not the case for pristine 1T-TiSe2. A subtle
interplay of CDW and superconducting orders, however, appears in each of these materials via chemical
intercalation or under pressure. Such a competition between or coexistence of proximate broken-symmetry
phases resembles many aspects of the phase diagram of cuprate high temperature superconductors
(HTSCs)—particularly, in the underdoped regime where the enigmatic pseudogap phase exists. The origin
of the CDW order in these compounds is an intriguing puzzle despite decades of research. We will present
our experimental data, which combine Angle Resolved Photoemission Spectroscopy, Scanning Tunneling
Spectroscopy, scattering and transport measurements, to provide new insights into the relative importance
of lattice and Coulomb effects in the CDW transitions of these compounds. These studies will also highlight
the distinctive impacts of disorder and doping in commensurate and incommensurate CDW systems.
Finally, comparing spectroscopic features of the CDW state of the TMDs with those of the normal state
underdoped HTSCs, we will discuss whether a CDW order can possibly be the origin of the pseudogap
phase in the cuprates.
Friday, September 28, 2018
3:30 PM
Physics Building, Room 204
Note special room.
"Feynmanʼs Footprints: Quantum Field Theory in Nuclear and Particle Physics"
Roxanne Springer , Duke University
[Host: Simonetta Liuti]
2018 is the 100th Anniversary of the birth of Richard Feynman.
His discoveries and new formalisms, and the way he thought about
solving problems, transformed the way we think
about physics. I will talk about examples of how these impacted present results
in nuclear and particle physics.
I will also expand upon what might be called Feynmanʼs Scientific Method,
and how by following that method we can become better scientists ourselves
and nurture the next generation of scientists.
Monday, September 24, 2018
3:30 PM
Physics Building, Room 203
Note special date.
Note special room.
Is gravity a fundamental force? I will discuss a few scenarios in which gravity emerges from the dynamics of some underlying field theory. In holography (or AdS/CFT correspondence), Einstein's equations for the bulk gravity dual are linked to entanglement in the boundary field theory. In another example, the graviton emerges as a composite spin two massless particle in a scalar field theory.
Friday, September 7, 2018
3:30 PM
Physics Building, Room 204
Note special room.
"Searching for Supersymmetry with the ATLAS experiment"
Evelyn Thomson , University of Pennsylvania
[Host: Chris Neu]
The ATLAS experiment is searching new territory for evidence of new particles produced in proton collisions at the highest energies. Questioning assumptions is important in these searches. I will compare selected results from searches for supersymmetry with and without the assumption of R-Parity, a quantum number derived from the spin and type of particle. I will also present some of the detector-related challenges associated with measuring charged particle momenta, including the planned upgrade of the detector to cope with up to 200 proton collisions every 25 nanoseconds.
Friday, April 27, 2018
3:30 PM
Physics Building, Room 204
Note special room.
I will review the current theoretical and phenomenological status of neutrino physics. In more detail, I will discuss our current understanding of neutrino properties, open questions, some new physics ideas behind nonzero neutrino masses, and the challenges of piecing together the neutrino mass puzzle. I will also comment on the new physics reach of the current and the next generation of neutrino oscillation experiments.
Thursday, April 26, 2018
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
"High-Q Optical Micro-cavities: Towards Integrated Optical Time Standards and Frequency Synthesizers"
Kerry Vahala , Caltech
[Host: OSA/SPIE Student Chapter]
Communication systems leverage the respective strengths of optics and electronics to convey high-bandwidth signals over great distances. These systems were enabled by a revolution in low-optical-loss dielectric fiber, complex integrated circuits as well as devices that link together the optical and electrical worlds. Today, another revolution is leveraging the advantages of optics and electronics in new ways. At its center is the laser frequency comb which provides a coherent link between these two worlds. Significantly, because the link is also bidirectional, performance attributes previously unique to electronics and optics can be shared. The end result has been transformative for time keeping, frequency metrology, precision spectroscopy, microwave-generation, ranging and other technologies. Even more recently, low-optical-loss dielectrics, now in the form of high-Q optical resonators, are enabling the miniaturization of frequency combs. These new `microcombs’ can be integrated with electronics and other optical components to potentially create systems on-a-chip. I will briefly overview the history and elements of frequency combs as well as the physics of the new microcombs. Application of the microcombs for spectroscopy and LIDAR will be discussed. Finally, efforts underway to develop integrated optical clocks and integrated optical frequency synthesizers using the microcomb element are described.
Friday, April 20, 2018
3:30 PM
Physics Building, Room 204
Note special room.
"Teaching physics as it is done: A plea for qualitative methods "
Prof. Jean-Marc Lévy-Leblond (Emeritus)
[Host: Olivier Pfister]
It is customary for young physicists, when entering their professional career, to be astonished by the huge difference between physics as it is done and physics as it is taught. The purpose is to show that teaching of physics as it is done is indeed possible and should be encouraged, despite the undeniable existence of didactical, epistemological and institutional obstacles.
Friday, April 13, 2018
3:30 PM
Physics Building, Room 204
Note special room.
"Using Dynamic Interferometry to Measure Optics of Next Generation Telescopes"
James Wyant , University of Arizona
[Host: OSA/SPIE Student Chapter]
There are currently several large telescope projects. One new telescope is the James Webb Space Telescope (JWST) which is planned to be launched into space on an Ariane 5 rocket from French Guiana in Spring 2019. It is expected that JWST will be the premier observatory of the next decade, serving thousands of astronomers worldwide. It will study every phase in the history of our Universe, ranging from the first luminous glows after the Big Bang, to the formation of solar systems capable of supporting life on planets like Earth, to the evolution of our own Solar System. The primary mirror will consist of 18 mirror segments made of beryllium coated with gold to give a total aperture diameter of 6.5 m. It is critical that the 18 mirror segments are properly phased so they perform as a single 6.5 m diameter mirror. JWST's backplane is the large structure that holds and supports the big hexagonal mirrors of the telescope. The backplane has an important job as it must carry not only the 6.5 m diameter primary mirror plus other telescope optics, but also the entire module of scientific instruments. The mechanical stability and thermal characteristics of the graphite composite backplane are extremely important for optimum performance of the telescope. JWST has many challenging optical testing requirements including a) Primary mirror figure testing, b) Back structure measurement, c) Segment phasing, d) Thermal and mechanical strain, and e) Vibrational dynamics.
Another telescope currently being constructed is the Giant Magellan Telescope (GMT), a large ground-based telescope consisting of seven 8.5 m diameter mirrors that will be built on a peak in the Andes Mountains near several existing telescope facilities at Las Campanas, Chile at an altitude of over 2,550 meters. The seven 8.4 m diameter mirror segments will be phased to give a telescope having the resolving power of a telescope 24.5 meters in diameter. GMT is expected to be operational for many decades, enabling breakthrough science ranging from studies of the first stars and galaxies in the universe to the exploration of extrasolar alien worlds. The GMT is poised to answer some of humanity’s biggest questions about the nature of exoplanets and whether we are alone in the universe, about the beginning of the universe to understand the formation and evolution of the galaxies, about the origin of the chemical elements, and how black holes grow. Like the JWST, the GMT has many challenging testing requirements.
During this talk we will describe the JWST and the GMT and the dynamic interferometry techniques that have been developed to measure high quality large telescope optics and the surface vibration and stability characteristics of the supporting structure required for high-quality performance large telescopes.
Friday, April 6, 2018
3:30 PM
Physics Building, Room 203
Note special room.
"What are Gravitational Waves telling us about Theoretical Physics "
Nicolas Yunes , Montana State University
[Host: Kent Yagi]
The recent gravitational wave observations of the collision of black holes and of neutron stars have allowed us to pierce into the extreme gravity regime, where gravity is simultaneously unfathomably large and wildly dynamical. These waves encode a trove of information about physics that is prime for the taking, including potential revelations about the validity of Einstein's theory of General Relativity and about nuclear physics in the extreme gravity regime. In this talk, I will describe some of the inferences we can make on both theoretical and nuclear physics from current and future gravitational wave observations.
Friday, March 30, 2018
3:30 PM
Physics Building, Room 204
Note special room.
"Chasing Relativistic Electrons in Topological Quantum Materials"
Adam Kaminski , Iowa State and Ames Lab.
[Host: Utpal Chatterjee]
The discovery of Dirac fermions in graphene has inspired a search for Dirac and Weyl semimetals in three dimensions thereby making it possible to realize exotic phases of matter first proposed in particle physics. Such materials are characterized by the presence of nontrivial quantum electronic states, where the electron’s spin is coupled with its momentum and Fermi surfaces are no longer closed contours in the momentum space, but instead consist of disconnected arcs. This opens up the possibility for developing new devices in which information is stored and processed using spin rather than charge. Such platforms may significantly enhance the speed and energy efficiency of information storage and processing. In this talk we will discuss the electronic properties of several of newly discovered tellurium based topological quantum materials. In WTe2 we have observed a topological transition involving a change of the Fermi surface topology (known as a Lifshitz transition) driven by temperature. The strong temperature-dependence of the chemical potential that is at the heart of this phenomenon is also important for understanding the thermoelectric properties of such semimetals. In a close cousin, MoTe2, by using high-resolution laser based Angle Resolved Photoemission Spectroscopy (ARPES) we identify Weyl points and Fermi surface arcs, showing a new type of topological Weyl semimetal with electron and hole pockets that touch at a Weyl point. I will also present evidence for a new topological state in PtSn4, that manifests itself by presence of set of extended arcs rather than Dirac points, and so far is not yet understood theoretically. These results open up new directions for research aimed at enhancing topological responsiveness of new quantum materials.
Friday, March 23, 2018
3:30 PM
Physics Building, Room 204
Note special room.
"Statistical mechanics for networks of real neurons"
William Bialek , Princeton University
[Host: Marija Vucelja]
Thoughts, memories, percepts, and actions all result from the interactions among large numbers of neurons. Physicists have long hoped that these emergent behaviors could be described using ideas from statistical mechanics. Recent experimental developments have made it possible to monitor, simultaneously, the electrical activity in hundreds or even thousands of cells. I will describe surprisingly simple statistical physics models that provide a detailed, quantitative account of these data, and then turn to renormalization group ideas that allow us to search explicitly for some underlying simplicity. There are signs that real networks are described by non-trivial fixed points, setting the stage for more ambitious theorizing.
In the four hundred years since Galileo, the physics community has constructed a remarkably successful mathematical description of the world around us. From deep inside the atomic nucleus to the structure of the universe on the largest scales, from the flow air over the wing of an airplane to the flow of electrons in a computer chip, we can predict in detail what we see, and what will happen when we look in places we have never looked before. What are the limits to this predictive power? In particular, can we imagine a theoretical physicist’s approach to the complex and diverse phenomena of the living world? Is there something fundamentally unpredictable about life, or are we missing some deep theoretical principles that could bring the living world under the predictive umbrella of physics? Exploring this question gives us an opportunity to reflect on what we expect from our scientific theories, and on many beautiful phenomena. I hope to leave you with a deeper appreciation for the precision of life’s basic mechanisms, and with optimism about the prospects for better theories.
Friday, March 16, 2018
3:30 PM
Physics Building, Room 203
Note special room.
"Multi-messenger Astrophysics in Light of LIGO’s Recent Discoveries"
Imre Bartos , University of Florida
[Host: Kent Yagi]
The recent discoveries of gravitational waves unveiled numerous opportunities in astrophysics, as well as in the study of the cosmos and the laws of physics. In particular, the multi-messenger detection of binary neutron-star merger GW170817 through gravitational waves and across the electromagnetic spectrum already delivered several important results. I will outline what we learned from GW170817 so far (its remnant is still observable!), along with the opportunities and challenges of near-future multi-messenger observations that will broaden our horizon with gravitational waves in the next few years. We can expect the proliferation of detected binary neutron star and binary black hole mergers, along with the large-scale efforts to rapidly identify the electromagnetic and neutrino counterparts of these events. Frequent multi-messenger observations will enable the study of exceptional events, source populations, and sufficient statistics to probe new physics and cosmology.
Friday, March 2, 2018
3:30 PM
Physics Building, Room 204
Note special room.
"Quantum gas microscopy of many-body dynamics in Fermi-Hubbard and Ising systems"
Peter Schauss , Princeton University
[Host: Bob Jones]
The ability to probe and manipulate cold atoms in optical lattices at the atomic level using quantum gas microscopes enables quantitative studies of quantum many-body dynamics. While there are many well-developed theoretical tools to study many-body quantum systems in equilibrium, gaining insight into dynamics is challenging with available techniques. Approximate methods need to be benchmarked, creating an urgent need for measurements in experimental model systems. In this talk, I will discuss two such measurements. First, I will present a study that probes the relaxation of density modulations in the doped Fermi-Hubbard model. This leads to a hydrodynamic description that allows us to determine the conductivity. We observe bad metallic behavior that we compare to predictions from finite-temperature Lanczos calculations and dynamical mean field theory. Second, I introduce a new platform to study the 2D quantum Ising model. Via optical coupling of atoms in an optical lattice to a low-lying Rydberg state, we observe quench dynamics in the resulting Ising model and prepare states with antiferromagnetic correlations.
Thursday, March 1, 2018
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
"Optical and transport properties of geometric metals"
Dmytro Pesin , University of Utah
[Host: Israel Klich ]
The effects of band geometry on measurable properties of electronic systems have been one of the central subjects in the recent history of condensed matter physics. In this talk, I will describe how non-trivial topology and, more generally, geometry of gapless electronic phases manifest in their optical and transport characteristics. The main focus of the talk will be on optical anomalous Hall effect and optical activity of Weyl metals, kinetic magnetoelectric effect in noncentrosymmetric conductors, as well as disorder physics in these materials.
Friday, February 23, 2018
3:30 PM
Physics Building, Room 204
Note special room.
"Quantum Mixology: Creating Novel Interacting Bose-Fermi Mixtures with Cs and Li"
Brian DeSalvo , University of Chicago
[Host: Bob Jones]
A gas of atoms cooled to sufficiently low temperature will form either a Bose-Einstein condensate (BEC) or a degenerate Fermi gas (DFG) depending on the quantum statistics of the constituent particles. But what happens when you combine a BEC and a DFG in an optical trap and add a healthy dose of interspecies interactions? Mean-field theory predicts three possible outcomes: a miscible mixture for weak interactions, complete demixing for strong repulsive interactions, or a spectacular collapse due to the loss of mechanical stability for strong attractive interactions. In this talk, I will discuss our efforts to answer this question experimentally in the specific case where the bosons are much heavier than the fermions. To this end, we have created the first quantum degenerate mixture of bosonic 133Cs and fermionic 6Li and used an interspecies Feshbach resonance to tune the interactions between the bosons and fermions. For attractive interspecies interactions, we find two surprising results. First, we show that a degenerate Fermi gas of Li can be trapped by a Cs BEC, even in the absence of external potentials. Second, for strong attractive interactions where collapse is predicted, we observe no such instability. I will discuss the mechanisms at play to explain these results and comment on current and future studies delving deeper into these unexpected regimes.
Monday, February 19, 2018
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
"New Frontiers of Electromagnetic Phenomena at the Nanoscale"
Wade Hsu , Yale University
[Host: Bob Jones]
Optics and photonics today enjoy unprecedented freedom. The ability to synthesize arbitrary light fields (through wavefront shaping) and the ability to design structures at the subwavelength scale (through nanofabrication) enable us to realize phenomena that could only be imagined in the past. In this talk, I will present several experiments and related theory that demonstrate exciting new phenomena which were previously inaccessible. A) Conventional textbook wisdom is that waves cannot be perfectly confined within the continuum spectrum of an open systems. Exceptions called “bound states in the continuum” were hypothesized by von Neumann and Wigner [1] but not realized. I will describe the first realization of such unusual states [2] and their manifestation as polarization vortices protected by topologically conserved “charges” [3]. B) Our ability to control radiation also enables the realization of non-Hermitian phenomena with no counterpart in closed systems. I will show how non-Hermiticity generates unique topologies in photonic band structures and lead to enhanced light–matter interactions [4,5]. C) Strong disorder in naturally occurring light-scattering media allows us to study mesoscopic physics in a new arena. I will describe the control of optical transport via wavefront shaping, and how the long-range correlations between multiply scattered photons enable us to simultaneously control orders of magnitudes more degrees of freedom than previously thought possible [6,7].
[1] C. W. Hsu*, B. Zhen* et al., Nature Reviews Materials 1, 16048 (2016).
[2] C. W. Hsu*, B. Zhen* et al., Nature 499, 188 (2013).
[3] B. Zhen*, C. W. Hsu* et al., Phys. Rev. Lett. 113, 257401 (2014).
[4] B. Zhen*, C. W. Hsu* et al., Nature 525, 354 (2015).
[5] H. Zhou et al., Science, eaap9859 (2018).
[6] C. W. Hsu et al., Phys. Rev. Lett. 115, 223901 (2015).
[7] C. W. Hsu et al., Nature Physics 13, 497 (2017).
Friday, February 16, 2018
3:30 PM
Physics Building, Room 204
Note special room.
"Topological and nonreciprocal dynamics in an optomechanical system"
Haitan Xu , Yale University
[Host: Bob Jones]
Non-Hermitian systems exhibit rich physical phenomena that open the door to qualitatively new forms of control. In this talk, I will introduce our recent work on topological and nonreciprocal dynamics in a non-Hermitian optomechanical system. Specifically, we realized topological energy transfer between nearly degenerate modes by adiabatically encircling an exceptional point (a singularity of the complex spectrum). We also demonstrated that this energy transfer is non-reciprocal: a given topological operation can only transfer energy in one direction. We have extended the topological and nonreciprocal dynamics to highly non-degenerate modes by exploiting a generic form of nonlinearity, which should allow these effects to be exploited in a very wide range of physical systems. In addition, we realized nonreciprocal dynamics by optomechanical interference.
Monday, February 12, 2018
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
"Quantum Molecular Dynamics of Strongly Correlated Electron Materials"
Gia-Wei Chern , UVA-Department of Physics
I will present a new formulation of quantum molecular dynamics for strongly correlated materials. Our novel scheme enables the study of the dynamical behavior of atoms and molecules with strong electron correlations. In particular, our scheme is based on the efficient Gutzwiller method that goes beyond the conventional mean-field treatment of the intra-atomic electron repulsion and captures crucial correlation effects such as band narrowing and electron localization. We use Gutzwiller quantum molecular dynamics to investigate the Mott metal-insulator transition in the liquid phase of a single-band metal and uncover intriguing structural and transport properties of the atoms. I will also discuss future plans for large-scale dynamical simulations of strongly correlated systems.
Friday, February 9, 2018
3:30 PM
Physics Building, Room 203
Note special room.
"A Rare and Prolific r-process Event Preserved in an Ultra-Faint Dwarf Galaxy"
Alexander Ji , Carnegie Observatories
[Host: Xiaochao Zheng]
The heaviest elements in the periodic table are synthesized through the rapid neutron-capture process (r-process), but the astrophysical site producing these elements has been a long-standing conundrum. Ultra-faint dwarf galaxies contain a simple fossil record of early chemical enrichment that provide an ideal laboratory to investigate the origin of r-process elements. Previous measurements found very low levels of neutron-capture elements in ultra-faint dwarfs, preferring supernovae as the r-process site. I present high-resolution chemical abundances of nine stars in the recently discovered ultra-faint dwarf Reticulum II, which display extremely enhanced r-process abundances 2-3 orders of magnitude higher than the other ultra-faint dwarfs. Stars with such extreme r-process enhancements are only rarely found in the Milky Way halo. The r-process abundances imply that the neutron-capture material in Reticulum II was synthesized in a single prolific event that is incompatible with r-process yields from ordinary core-collapse supernovae but consistent with a neutron star merger. Together with the recent gravitational wave observations of a neutron star merger and its electromagnetic afterglow, it is now clear that neutron star mergers dominate cosmic production of r-process elements.
Thursday, February 8, 2018
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
"Electron hydrodynamics in solid-state physics"
Thomas Scaffidi , University of California, Berkeley
[Host: Israel Klich]
Wolfgang Pauli called solid-state physics "the physics of dirt effects", and this name might appear well-deserved at first sight since transport properties are more often than not set by extrinsic properties, like impurities. In this talk, I will present solid-state systems in which electrons behave hydrodynamically, and for which transport properties are instead set by intrinsic properties, like the viscosity. This new regime of transport opens the way for a “viscous electronics”, and provides a new angle to study how quantum mechanics can constrain and/or enrich hydrodynamics.
Wednesday, February 7, 2018
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
"A programmable quantum computer based on trapped ions"
Norbert Linke , Joint Quantum Institute, University of Maryland, and NIST
[Host: Bob Jones]
Quantum computers can solve certain problems more efficiently than any classical computer. Trapped ions are a promising candidate for realizing such a system. We present a modular quantum computing architecture comprised of a chain of 171Yb+ ions with individual Raman beam addressing and individual readout [1]. We use the transverse modes of motion in the chain to produce entangling gates between any qubit pair. This creates a fully connected system which can be configured to run any sequence of single- and two-qubit gates, making it in effect an arbitrarily programmable quantum computer that does not suffer any swap-gate overhead [2].
Recent results from different quantum algorithms on five and seven ions will be presented [3,4], including a quantum error detection protocol that fault-tolerantly encodes a logical qubit [5]. I will also discuss current work and ideas to scale up this architecture.
[1] S. Debnath et al., Nature 563:63 (2016).
[2] NML et al., PNAS 114 13:3305 (2017).
[3] C. Figgatt et al., Nat. Communs. 8, 1918 (2017).
[4] NML et al., arXiv:1712.08581 (2017)
[5] NML et al., Sci. Adv. 3, 10 (2017).
Monday, February 5, 2018
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
"Quantum sensing in a new single-molecule regime"
Peter Maurer , Stanford University
[Host: Bob Jones]
Quantum optics has had a profound impact on precision measurements, and recently enabled probing various physical quantities, such as magnetic fields and temperature, with nanoscale spatial resolution. Such advancements in ‘quantum sensing’ have brought the elusive dream of performing nuclear magnetic resonance spectroscopy (NMR) on individual biomolecules closer to reality. In my talk, I will discuss the development and application of novel quantum metrological technologies to study biological systems at a single-molecule level. I will start with a general introduction to quantum sensing, with a focus on the measurement of magnetic fields at a nanoscale. I will then show how we utilize such sensing techniques to control the temperature profile in living systems with subcellular resolution. Finally, I will provide an outlook on how quantum sensing and single-molecule biophysics can be utilized to perform NMR spectroscopy with unprecedented sensitivity, possibly down to the level of individual biomolecules.
Friday, February 2, 2018
3:30 PM
Physics Building, Room 204
Note special room.
"Topological Superconductivity From Electronic Interactions"
Yuxuan Wang , UIUC
[Host: Israel Klich ]
Topological superconductors exhibit exotic Majorana modes at the boundaries and vortices, and can provide important applications in quantum computing. In addition to usual path of “engineering” topological superconductivity with heterostructure of conventional superconductors, we show that intrinsic topological superconductivity can also be naturally realized through electron-electron interactions. Specifically, we analyze the topological superconducting state that emerges near the onset of an inversion-breaking electronic order. Other than topological superconductivity, we show that the system has an enhanced U(1)xU(1) symmetry as well as a rich phase diagram. We address the relevance of our results with recent experiments in Cd2Ce2O7 and half-Heusler superconductors. We argue that important progress can be made at the intersection of topological superconductivity and unconventional superconductivity.
Friday, January 26, 2018
3:30 PM
Physics Building, Room 204
Note special room.
"Imprints of complex landscapes on glassy materials"
Sho Yaida , Duke University
[Host: Israel Klich ]
Amorphous solids are omnipresent in everyday life, from window glasses to plastics to piles of sand. Yet our understanding of their properties lags far behind that of their crystalline counterparts. Recent advances are rapidly changing the way in which we understand these materials. This talk overviews two such advances: (i) the algorithmic developments that link dramatic slowdown of glass-forming liquids to growing amorphous order, and (ii) the discovery of the critical replica-symmetry-breaking transition within solid glasses. Taken together, these results reinforce the overriding role of rugged free-energy landscapes in controlling glassiness.
Tuesday, January 23, 2018
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
The past decade's apparent success in predicting and experimentally discovering distinct classes of topological insulators (TIs) and semimetals masks a fundamental shortcoming: out of 200,000 stoichiometric compounds extant in material databases, only several hundred of them are topologically nontrivial. Are TIs that esoteric, or does this reflect a fundamental problem with the current piecemeal approach to finding them? To address this, we propose a new and complete electronic band theory that highlights the link between topology and local chemical bonding, and combines this with the conventional band theory of electrons. We classify the possible band structures for all 230 crystal symmetry groups that arise from local atomic orbitals, and show which are topologically nontrivial. We show how our topological band theory sheds new light on known TIs, and demonstrate the power of our method to predict new TIs.
Friday, January 19, 2018
3:30 PM
Physics Building, Room 204
Note special room.
"Constraints on multiparticle entanglement"
David Meyer , University of California at San Diego
[Host: Olivier Pfister]
States of a multiparticle quantum system are useful for quantum information processing when they are entangled, i.e., not product states relative to the tensor product decomposition of the Hilbert space corresponding to the particles. Arbitrary entanglements between parts of a quantum system are not possible, however; they must satisfy certain “monogamy” constraints which limit how much multiple different subsystems can be entangled with one another. The standard monogamy constraints can be generalized in several ways: in this talk we’ll tighten some, generalize others to higher dimensional tensor factors, and derive inequalities satisfied by symmetric sets of entanglement measures. Along the way we’ll contrast the quantum results with corresponding statements about classical random variables.
Friday, December 1, 2017
3:30 PM
Physics Building, Room 204
Note special room.
In classical mechanics, chaos refers to the phenomenon that an arbitrarily small perturbation leads to a dramatic change at a later time. The analogous phenomenon in quantum mechanics---quantum chaos is generic in many-body systems. Although chaos makes it difficult to solve the many-body problem exactly, it actually provides new knowledge about dynamics of the system, such as thermalization. In understanding quantum chaos and thermalization, the concept of quantum entanglement plays an essential role. In this talk, I will discuss the connection between several related phenomena, including the dynamics of quantum entanglement, thermalization of isolated systems, and measure of quantum chaos. As a concrete model to study quantum chaos, I will discuss the Sachdev-Ye-Kitaev (SYK) model and its generalizations. This model provides an example of strongly correlated systems in which new kinds of "order" emerges from chaos. Entanglement dynamics in this model suggests an interesting interplay between thermalization and many-body localization.
References: arXiv:1511.04021
Friday, November 17, 2017
3:30 PM
Physics Building, Room 204
Note special room.
Recent theoretical advances in the mean-field theory of glasses predict the existence, deep in the glass phase, of a novel phase transition, a so-called Gardner transition. This transition signals the emergence of a complex free energy landscape composed of a marginally stable hierarchy of sub-basins. It is also thought to be the onset of the anomalous thermal and transport properties of amorphous systems, and to ultimately lead to the unusual critical behavior at jamming. In this talk, I will present an overview of our recent theoretical and numerical advances in capturing and characterizing this novel materials feature.
Friday, November 10, 2017
3:30 PM
Physics Building, Room 204
Note special room.
"Bad Metal Behavior and Mott Quantum Criticality"
Vladimir Dobrosavljevic , Florida State University
[Host: Gia-Wei Chern]
According to early ideas of Mott and Anderson, the interaction-driven metal-insulator transition “the Mott transition“ remains a sharp T=0 phase transition even in absence of any spin or charge ordering. Should this phase transition be regarded as a quantum critical point? To address this question, here we examine the phase diagram and transport properties of the maximally frustrated half-filled Hubbard model, in the framework of dynamical mean-field theory (DMFT). We identify a quantum Widom line (QWL) which defines the center of the corresponding quantum critical region associated with Mott metale insulator transition for this model. The evolution of resistivity with temperature is then evaluated along trajectories following (parallel to) the QWL, displaying remarkable scaling behavior characteristic of quantum criticality. Precisely this kind of behavior was found in very recent experiments on organic Mott systems [1,2]. In the case of the doping-driven Mott transition, we show that the mysterious Bad Metal behavior (T-linear resistivity around the Mott-Ioffee- Regel limit) coincides with the Quantum Critical region of the Mott transition.
[1] Quantum criticality of Mott transition in organic materials, Tetsuya Furukawa, Kazuya Miyagawa, Hiromi Taniguchi, Reizo Kato & Kazushi Kanoda, Nature Physics, 9 Feb. 2015; doi:10.1038/nphys3235.
[2] See also:
http://condensedconcepts.blogspot.com/2015/03/quantum-criticality-near-mott.html
Friday, November 3, 2017
3:30 PM
Physics Building, Room 204
Note special room.
"APS Bridge Program: Changing the Face of Physics Graduate Education"
Ted Hodapp , APS Bridge Program
[Host: Olivier Pfister]
In nearly every science, math, and engineering field there is a significant falloff in participation by underrepresented minority (URM) students who fail to make the transition between undergraduate and graduate studies. The American Physical Society (APS) has realized that a professional society can erase this gap by acting as a national recruiter of URM physics students and connecting these individuals with graduate programs that are eager to a) attract motivated students to their program, b) increase domestic student participation, and c) improve the diversity of their program. Now in its fifth year the APS has placed enough students into graduate programs nationwide to eliminate this achievement gap. The program has low costs, is popular among graduate programs, and has inspired other departments to adopt practices that improve graduate admissions and student retention. This presentation will review project activities, present data that demonstrate effectiveness, and discuss future actions.
This material is based upon work supported in part by the National Science Foundation under Grant No. (NSF-1143070).
Friday, October 27, 2017
3:30 PM
Physics Building, Room 204
Note special room.
"Lifting the Bandwidth Limit of Optical Homodyne Measurement - A Key for Broadband Quantum Information"
Avi Pe'er , Bar Ilan University
[Host: OSA/SPIE Student Chapter]
Homodyne measurement is a corner-stone of quantum optics. It measures the fundamental variables of quantum electrodynamics - the quadratures of light, which represent the cosine-wave and sine-wave components of an optical field. The quadratures constitute the quantum optical analog of position and momentum in mechanics and obey quantum uncertainty, indicating the inherent inability to measure both simultaneously. The homodyne process, which extracts a chosen quadrature amplitude by correlating the optical field against an external quadrature reference (local-oscillator, LO), forms the backbone of coherent detection in physics and engineering, and plays a central role in quantum information processing. Homodyne can reveal non-classical phenomena, such as squeezing of the quadrature uncertainty; It is used in tomography to fully characterize quantum states of light; Homodyne detection can generate non-classical states, provide local measurements for teleportation and serve as a major detector for quantum key distribution (QKD) and quantum computing. Yet, standard homodyne suffers from a severe bandwidth limitation. While the bandwidth of optical states can easily span many THz, standard homodyne detection is inherently limited to the electrically accessible, MHz to GHz range, leaving a dramatic gap between the relevant optical phenomena and the measurement capability. This gap impedes effective utilization of the huge bandwidth resource of optical states and the potential enhancement of the information throughput \emph{by several orders of magnitude} with parallel processing in quantum computation, QKD and other applications of quantum squeezed light. Here we demonstrate a fully parallel optical homodyne measurement across an arbitrary optical bandwidth, effectively lifting the bandwidth limitation completely. Using optical parametric amplification, which amplifies one quadrature while attenuating the other, we measure two-mode quadrature squeezing of 1.7dB below the vacuum level simultaneously across a bandwidth of 55THz using a single LO - the pump. This broadband parametric homodyne measurement opens a wide window for parallel processing of quantum information.
Yaakobv Shaked, Yoad Michael, Rafi Vered, Leon Bello, Michael Rosenbluh and Avi Pe'er, Physics Dept. and BINA center for Nanotechnology, Bar Ilan University, Ramat Gan 5290002, Israel
Friday, October 20, 2017
3:30 PM
Physics Building, Room 204
Note special room.
The history of our exploration of subatomic matter has witnessed a major breakthrough with every new probe being introduced. In the 1950’s Hofstadter and collaborators using elastic electron scattering measured for the first time the electromagnetic form factors of nucleons and nuclei and provided the first information on the nuclear spatial charge and magnetization distributions. In the late 1960’s and early 70’s, Friedman, Kendall and Taylor using Deep Inelastic Scattering of electrons off the nucleon, discovered its underlying quark structure displayed in their longitudinal momentum distributions.
I will discuss probes at the next frontier that will allow us to access dynamically correlated distributions in both momentum and coordinate space -- the Wigner distributions -- at the femtoscale. Deeply Virtual Compton Scattering, namely a high energy lepton scattering off a nucleon target producing a high energy real photon and a small angle recoil proton, is one of such probes. I will explain how a detailed mapping of the quarks and gluons in the nucleon and nucleus in phase space, or a phase-space tomography, besides providing for the first time images of quarks and gluons spatial distributions, is essential for understanding the so far elusive nucleon mass and spin decompositions in terms of its quark and gluon components.
Friday, October 13, 2017
3:30 PM
Physics Building, Room 204
Note special room.
"All-optical Switching for Photonic Quantum Networks"
Prem Kumar , Northwestern University
[Host: Olivier Pfister]
Quantum internet of the future will require device functionalities that implicitly respect the fundamental facts such as quantum information cannot be copied, and cannot be measured precisely. A quantum repeater, for example,—analog of an optical amplifier that enabled global reach of the ubiquitous Internet connectivity we enjoy today—is yet to be demonstrated, although recent years have seen tremendous progress. Many other device functionalities—switches, routers, format converters, etc.—would also be needed that do not unnecessarily disturb or corrupt the quantum information as it flows from one node of the internet to another. In recent years, my group has engineered an all-optical quantum switch that fulfills many of the requirements for distributing quantum information in a networked environment. In this talk, I will present our motivation, design, construction, characterization, and utilization of such a switch in near-term networked quantum applications.
Friday, October 6, 2017
3:30 PM
Physics Building, Room 204
Note special room.
"Looking for New Physics with the Weak Interaction in Electron Scattering: Recent Results from Qweak and Future Perspectives"
Kent Paschke , UVA-Physics
[Host: Joe Poon]
The measurement of the violation of parity symmetry in electron scattering has proven to be a powerful technique for exploring nuclear matter and searching for new fundamental forces. In the Standard Model of particle physics, parity violation can only occur through the weak interaction. Precision measurements of this symmetry breaking can test the completeness of this description of the weak force at low energies. I will describe the result of one such measurement - the recently completed Qweak experiment - along with the experimental challenges and triumphs. Future measurements in the field of parity-violating electron scattering will also be reviewed, including other Standard Model tests and experiments using the weak force to determine the size of a heavy atomic nucleus.
Friday, September 29, 2017
3:30 PM
Physics Building, Room 204
Note special room.
The word "atom" (a-tomos) originates from ancient Greek philosophers, who argued that objects can be eventually divided into discrete, small particles, beyond which matter is no longer cuttable. Our search for the answer to "What the matter is made of" has gone a long way, from the first experimental evidence of atoms in the 1800's, to Rutherford's alpha scattering on gold foils, to modern day's linear accelerators looking into the atomic nucleus. We now understand that matter is made of quarks and leptons, currently named elementary particles (objects of no size) that form the foundation of the Standard Model of Particle Physics. However, if we look back at this journey, one may wish to oppose the view of the ancient Greeks and argue that quarks and leptons cannot be the end of the story, that our quest for peeling the atomic onion may be a timeless journey.
I will discuss the frontier research in electron scattering at the GeV energy level. I will focus on parity violation in electron scattering off the proton and the neutron and the extraction of neutral-weak effective couplings between electrons and quarks, and show how such high precision measurements are now helping us venturing further into the study of subatomic structure.
Friday, September 22, 2017
3:30 PM
Physics Building, Room 204
Note special room.
The Laser Interferometer Gravitational-wave Observatory (LIGO) detected gravitational waves for the first time in 2015. Since then there have been a couple more detections of binary black hole mergers. I will discuss the instruments that made these discoveries, the science so far, and plans for future improvements and upgrades to LIGO.
Thursday, September 21, 2017
7:00 PM
Chemistry Building, Room 402
Note special date.
Note special time.
Note special room.
"The Warped Universe: the one hundred year quest to discover Einstein’s gravitational waves"
Nergis Mavalvala , M.I.T.
In 2016, scientists announced the first ever detection of gravitational waves from colliding black holes, launching a new era of gravitational wave astrophysics. Gravitational waves were predicted by Einstein a hundred years earlier. I will describe the science, technology, and human story behind these discoveries that provide a window into some of the most violent and warped events in the Universe.
Friday, September 15, 2017
3:30 PM
Physics Building, Room 204
Note special room.
"Tune-out wavelength spectroscopy: a new technique to characterize atomic structure"
Cass Sackett , UVA-Physics
[Host: Joe Poon]
When you shine a laser on an atom, the electric field of the light induces a dipole moment, resulting in an energy shift. The dipole can be either parallel or anti-parallel to the field, depending on the frequency of the light. This corresponds to negative or positive energies. At certain frequencies, however, the induced dipole is zero. The corresponding light wavelength is called a tune-out wavelength. The location of the various tune-out wavelengths depend on the electronic wave function in the atom, particularly the dipole matrix elements . So by measuring the tune-out wavelength, the dipole matrix elements can be determined more accurately than by conventional techniques. This is useful because the dipole matrix elements are also used to relate precision atomic experiments like parity violation to fundamental particle properties like the weak mixing angle. We have developed a new technique for measuring tune-out wavelengths, which should improve our knowledge of many matrix elements by an order of magnitude or more. We hope that this will support new generations of precision atomic measurements.
Friday, September 8, 2017
3:30 PM
Physics Building, Room 204
Note special room.
"Origin of Long Lifetime of Band-Edge Charge Carriers in Organic-Inorganic Lead Iodide Perovskites"
Tianran Chen , UVA-Physics
[Host: Seunghun Lee]
Long carrier lifetime is what makes hybrid organic-inorganic perovskites high performance photovoltaic materials. Several microscopic mechanisms behind the unusually long carrier lifetime have been proposed, such as formation of large polarons, Rashba effect, ferroelectric domains, and photon recycling. Here, we show that the screening of band-edge charge carriers by rotation of organic cation molecules can be a major contribution to the prolonged carrier lifetime. Our results reveal that the band-edge carrier lifetime increases when the system enters from a phase with lower rotational entropy to another phase with higher entropy. These results imply that the recombination of the photo-excited electrons and holes is suppressed by the screening, leading to the formation of polarons and thereby extending the lifetime. Thus, searching for organic-inorganic perovskites with high rotational entropy over a wide range of temperature may be a key to achieve superior solar cell performance.
Friday, April 28, 2017
3:30 PM
Physics Building, Room 204
Note special room.
For over 50 years, people have been discussing the promise of high-energy neutrino astronomy. For most of that time, wholesale theoretical conjecture was unmatched by even a trifling return of measured experimental facts. Then in 2013, the IceCube neutrino observatory discovered astrophysical neutrinos with energies up to fifteen orders of magnitude above those of visible light. What does this mean for understanding astrophysical sources, the properties of neutrinos, and the contents of the Universe?
Friday, April 21, 2017
3:30 PM
Physics Building, Room 204
Note special room.
"Probing Molecular Dynamics from Within using FELs"
Nora Berrah , University of Connecticut
[Host: Despina Louca]
Short x-ray pulses from free electron lasers (FELs) open a new regime for all scientific research. The first x-ray FEL, the Linac Coherent Light Source (LCLS) at the SLAC National Laboratory on the Stanford campus, provides intense short pulses that allow the investigation of ultrafast non-linear and multi-photon processes, including time-resolved investigations in molecules. We will report on the femtosecond response of molecules to the ultra-intense, ultrafast x-ray radiation from FELs as well as on time-resolved investigation using x-ray pump-x-ray probe techniques.
"Negative resistance and other wonders of viscous electronics in graphene"
Gregory Falkovich , Weizmann Institute
[Host: Marija Vucelja]
Quantum-critical strongly correlated systems feature universal collision-dominated collective transport. Viscous electronics is an emerging field dealing with systems in which strongly interacting electrons flow like a fluid. We identified vorticity as a macroscopic signature of electron viscosity and linked it with a striking macroscopic DC transport behavior: viscous friction can drive electric current against an applied field, resulting in a negative resistance, recently measured experimentally in graphene. I shall also describe current vortices, expulsion of electric field, conductance exceeding the fundamental quantum-ballistic limit and other wonders of viscous electronics. Strongly interacting electron-hole plasma in high-mobility graphene affords a unique link between quantum-critical electron transport and the wealth of fluid mechanics phenomena.
http://www.nature.com/nphys/journal/vaop/ncurrent/full/nphys3667.html
Friday, April 7, 2017
3:30 PM
Physics Building, Room 204
Note special room.
"[CANCELED] Engineering Quantum Thermal Machines"
Adolfo Del Campo , University of Massachusetts
[Host: Israel Klich ]
Quantum thermodynamics has emerged as an interdisciplinary research field in quantum science and technology with widespread applications. Yet, the identification of scenarios characterized by quantum supremacy -a performance without match in the classical world- remains challenging. In this talk I shall review recent advances in the engineering and optimization of quantum thermal machines. I will show that nonadiabatic many-particle effects can give rise to quantum supremacy in finite-time thermodynamics [1]. Tailoring such nonadiabatic effects by making use of shortcuts to adiabaticity, quantum heat engines can be operated at maximum efficiency and arbitrarily high output power [2]. A thermodynamic cost of these shortcuts will be elucidated by analyzing the full work distribution function and introducing a novel kind of work-energy uncertainty relation [3]. I shall close by discussing the identification of scenarios with a quantum-enhanced performance in thermal machines run over many cycles [4].
Bibliography:
[1] J. Jaramillo, M. Beau, A. del Campo, New J. Phys. 18, 075019 (2016).
[2] M. Beau, J. Jaramillo, A. del Campo, Entropy 18, 168 (2016).
[3] K. Funo, J.-N. Zhang, C. Chatou, K. Kim, M. Ueda and A. del Campo, Phys. Rev. Lett, 118, 100602 (2017).
[4] G. Watanabe, B. P. Venkatesh, P. Talkner and A. del Campo, Phys. Rev. Lett. 118, 050601 (2017).
Friday, March 31, 2017
9:00 AM
The Rotunda, Room Dome Room
Note special time.
Note special room.
"Storage at the Threshold: Li-ion Batteries and Beyond"
George Crabtree , Joint Center for Energy Storage Research (JCESR) Argonne National Laboratory and University of Illinois at Chicago
[Host: Bellave Shivaram]
The high energy density and low cost of lithium-ion batteries have created a revolution in personal electronics through laptops, tablets, smart phones and wearables, permanently changing the way we interact with people and information. We are at the threshold of similar transformations in transportation to electric cars and in the electricity grid to renewable generation, smart grids and distributed energy resources. Many aspects of these transformations require new levels of energy storage performance and cost that are beyond the reach of Li-ion batteries. Next generation beyond Li-ion batteries and their potential to meet these performance and cost thresholds will be analyzed.
George Crabtree, Elizabeth Kocs and Lynn Trahey, The energy-storage frontier: Lithium-ion batteries and beyond, MRS Bulletin 40, 1067 (2015)
Bio: George Crabtree is Director of the Joint Center for Energy Storage (JCESR) at Argonne National Laboratory and Professor of Physics, Electrical, and Mechanical Engineering at University of Illinois-Chicago (UIC). He has wide experience in next-generation battery technology and integrating energy science, technology, policy and societal decision-making. He has led workshops for the Department of Energy on energy science and technology, is a member of the National Academy of Sciences and has testified before the U.S. Congress.
Friday, March 31, 2017
3:30 PM
Physics Building, Room 204
Note special room.
The High Altitude Water Cherenkov (HAWC) Gamma-ray Observatory was completed in March 2015 and is now giving us a new view of the sky. HAWC is a continuously operating, wide field-of-view observatory sensitive to 100 GeV – 100 TeV gamma rays and cosmic rays. It is 15 times more sensitive than previous generation extensive air shower gamma-ray instruments. It serves as a “finder” telescope and monitors the same sky as gamma-ray satellites (Fermi), gravity-wave (LIGO) detectors and neutrino observatories (IceCube) allowing for multi-wavelength and multi-messenger observations. HAWC hopes to answer questions such as "what is dark matter?” and “where do cosmic rays come from?” by observing some of the most violent processes in our Universe. I will present highlights from HAWC’s first year of operation.
"Controlling cell size and DNA replication in bacteria - insights from mathematical modeling"
Ariel Amir , Harvard University
[Host: Marija Vucelja]
Understanding how cells control and coordinate the various ongoing cellular processes, such as DNA replication, growth and division is an outstanding fundamental problem in biology. Remarkably, bacterial cells may divide faster than their chromosomes replicate, implying that cells maintain multiple rounds of chromosome replication, and that tight control over DNA replication must be in place. I will show how ideas from statistical mechanics and mathematical modeling can serve as alternative "microscopes" into this problem. Our results suggest that both cell size and chromosome replication may be simultaneously regulated by following a simple control mechanism, in which, effectively, a constant volume is added between two DNA replication initiation events. This model elucidates the experimentally observed correlations between various events in the cell cycle, and explains the exponential dependence of cell size on the growth rate, as well as recent experiments in which cell morphology is perturbed.
The IceCube project at the South Pole has melted eighty-six holes over 1.5 miles deep in the Antarctic icecap for use as astronomical observatories. The project recently discovered a flux of neutrinos reaching us from the cosmos, with energies more than a million times those of the neutrinos produced at accelerator laboratories. These neutrinos are astronomical messengers from some of the most violent processes in the universe--giant black holes gobbling up stars in the heart of quasars and gamma-ray bursts, the biggest explosions since the Big Bang.
In a special public lecture, brought to you by the departments of physics, astronomy, and NRAO Francis Halzen, Gregory Breit Professor and Hilldale Professor of Physics at UW-Madison and the principal investigator of IceCube, will tell the story of the IceCube telescope and discuss highlights from recent scientific results.
"Manipulating atoms with light: from spectroscopy to atomtronics"
Bill Phillips , NIST
[Host: Sanjay Khatri - OSA Student Chapter]
Physicists have used light and its polarization to elucidate the internal state of atoms since the 19th century. Early in the 20th century, the momentum of light was used to change the center-of-mass motion of atoms. The latter part of the 20th century brought optical pumping, coherent laser excitation, and laser cooling and trapping as tools to manipulate both the internal and external states of atoms. Atom optics techniques like diffraction of atoms from light provided the elements needed for atom-wave interferometers. Bose-Einstein condensation created atomic samples having laser-like deBroglie-wave coherence. Now, in the 21st century, the circulation of superfluid atoms in ring-shaped structures enables “atomtronic” circuitry—an atomic analog of superconduction electric circuits. We observe persistent flow of atoms in toroidal traps, and can introduce a weak-link (a kind of Josephson junction) that allows control of the quantized circulation of atoms.
Wednesday, March 1, 2017
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
"From Chirps to Jets: The extreme world of Black Holes and Neutron Stars"
Francois Foucart , Lawrence Berkeley National Lab
[Host: Peter Arnold]
Black holes and neutron stars are extraordinary astrophysical laboratories.
They allow us to test the laws of gravity and nuclear physics in extreme environments which cannot be reproduced on Earth. In this talk, I will discuss efforts to model these compact objects in two classes of astrophysical systems: mergers of black hole-neutron star and neutron star-neutron star binaries, and accretion disks around supermassive black holes. The first are powerful sources of gravitational waves, and emit bright electromagnetic transients. In the advanced gravitational wave detector era, they will provide us with new information about general relativity, the properties of matter above nuclear density, and the population of black holes and neutron stars. The second will soon be imaged by the Event Horizon Telescope with enough accuracy to resolve the horizon of two black holes, and to study the behavior of the nearly collisionless plasma accreting onto them. I will in particular focus on the role of numerical simulations using general relativistic codes, which will play a crucial role in our interpretation of these upcoming observations.
Tuesday, February 28, 2017
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
"Quantum alchemy for the 21st century: accessing new horizons of quantum many-body dynamics through periodic driving"
Mark Rudner
[Host: Israel Klich ]
Recent work on topological materials has revealed a wide variety of intriguing phenomena that may arise when particles move in "non-trivial" bands. At the same time, modern advances in experimental capabilities for controlling electronic, atomic, and optical systems open new possibilities for dynamically controlling the behaviors of a range of quantum systems. In this talk I will review the basic ideas behind topological band theory, and then explain how periodic driving can be used to gain dynamical control over the topological properties of quantum matter. In the driven case, intriguing new types of robust non-equilibrium topological phenomena emerge. To illustrate, I will show how the combination of driving, topology, and interactions can bring about a new regime of universal quantized transport, and discuss potential near-term experimental realizations.
**THE RECEPTION WILL BE HELD AT 3:00PM IN ROOM 313**
Monday, February 27, 2017
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
In the next few years, low-frequency radio telescopes will use the 21cm line of neutral hydrogen to make unprecedentedly large maps of our observable Universe. These will provide exquisite constraints on the properties of the first stars and galaxies. Along these lines, I will review recent results from the Precision Array to Probe the Epoch of Reionization (PAPER) experiment, which have begun to shed light on heating processes in the early universe. I will also discuss how comparing theory and observations will become difficult as one enters the regime of “big data” and theoretical models become increasingly complicated. I will describe how machine learning techniques make such comparisons computationally feasible. Finally, I will discuss the recently commenced Hydrogen Epoch of Reionization Array (HERA) experiment, including its forecasted ability to constrain fundamental parameters such as the neutrino mass. Looking to the future, I will highlight additional opportunities to constrain cosmology and particle physics using the 21cm line.
Thursday, February 23, 2017
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
"Progress and challenges in designing a universal Majorana quantum computer"
Torsten Karzig , Station Q, UCSB
[Host: Israel Klich ]
I will discuss a promising design proposal for a scalable topological quantum computer. The qubits are envisioned to be encoded in aggregates of four or more Majorana zero modes, realized at the ends of topological superconducting wire segments that are assembled into superconducting islands with significant charging energy. Quantum information can be manipulated according to a measurement-only protocol, which is facilitated by tunable couplings between Majorana zero modes and nearby semiconductor quantum dots. The key virtue of the proposed architecture is its modular and scalable design and a natural suppression of quasiparticle poisoning by charge protection.
In the second part of the talk I will comment on the importance of elevating these designs to full quantum universality by so called magic state injection. The latter relies on a high fidelity source of specific quantum states and I will point out some of ideas and challenges for providing them.
**THE RECEPTION WILL BE HELD AT 3:00PM IN ROOM 313**
Wednesday, February 22, 2017
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
"Gravitational waves from binary black holes across the spectrum"
Michele Vallisneri , Jet Propulsion Laboratory, Caltech
[Host: Peter Arnold]
On September 14, 2015, the two LIGO detectors simultaneously observed a transient gravitational-wave signal, which was named GW150914. The signal fit very precisely the general-relativistic prediction for the inspiral, merger, and ringdown of a pair of stellar-mass black holes, with component masses greater than was thought possible in standard evolution scenarios. This was the first direct detection of gravitational waves and the first observation of a binary black-hole merger. I describe the mechanics and behind-the-scenes of the detection, and its implications for astrophysics and fundamental physics. Two additional black-hole binaries were detected in LIGO's first observing run, and more are expected from current data taking. At the low-frequency side of the gravitational-wave spectrum, signals from massive black-hole binaries are targeted by the space-based observatory LISA, now on track for launch in the early 2030s, and by pulsar-timing arrays, with a positive detection expected in ten years. I discuss the science case, prospects, and requirements of these programs.
**THE RECEPTION WILL BE HELD AT 3:00PM IN ROOM 313**
Thursday, February 16, 2017
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
"Bosonic Symmetry Protected Topological States: Theory, Numerics, and Experimental Platform"
Yi-Zhuang You , Harvard University
[Host: Israel Klich ]
Topological phases of matter is an active research area of condensed matter physics. Among various topics, the bosonic symmetry protected topological (BSPT) states have attracted enormous theoretical interest in the last few years. BSPT states are bosonic analogs of topological insulators. The Haldane phase of spin-1 chains is one famous example. I will talk about our recent proposal to realize two-dimensional BSPT states in the twisted bilayer graphene with strong magnetic field, as well as numerical simulations of the lattice model in various parameter regimes. The proposed BSPT state is a quantum spin Hall insulator with bosonic boundary modes only. The bosonic modes are spin and charge collective excitations of electrons. The quantum phase transition between the topological and the trivial phases happens by closing the gap of bosonic modes in the bulk, without closing the single particle gap of electrons, which is fundamentally different from all the well-known topological transitions in free fermion topological insulators. On the theory side, the phase transition is related to topics of deconfined criticality and duality of (2+1)D conformal field theories. The theoretical, numerical and experimental studies will deepen our understanding of quantum phase transitions.
**THE RECEPTION WILL BE HELD AT 3:00PM IN ROOM 313**
Wednesday, February 15, 2017
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
" Probing Extreme Gravity with Black Holes and Neutron Stars"
Kent Yagi , Princeton University
[Host: Peter Arnold]
Black holes and neutron stars are extremely compact astrophysical objects that are produced after the death of very massive stars. Due to their large compactness and population, such compact objects offer us excellent testbeds for probing fundamental physics. In this talk, I will focus on probing extreme (strong and dynamical-field) gravity that was previously inaccessible. Regarding black hole based tests of gravity, I will explain how stringently one can probe various fundamental pillars in General Relativity with the recently-discovered gravitational wave events. Regarding neutron star based tests of gravity, I will use approximate universal relations ("I-Love-Q relations") among certain neutron star observables that are almost insensitive to the unknown stellar internal structure, and describe how one can probe extreme gravity by combining future gravitational wave and binary pulsar observations. I will conclude with a summary of important future directions.
Friday, February 10, 2017
3:30 PM
Physics Building, Room 204
Note special room.
"Superconductivity from repulsion"
Andrey Chubukov , University of Minnesota
[Host: Genya Kolomeisky]
In my talk, I review recent and not so recent works aiming to understand whether a nominally repulsive Coulomb interaction can by itself give rise to a superconductivity. I discuss a generic scenario of the pairing by electron-electron interaction, put forward by Kohn and Luttinger back in 1965, and modern studies of the electronic mechanisms of superconductivity in the lattice systems which model cuprates, Fe-pnictides, and doped graphene. I show that the pairing in all three classes of materials can be viewed as a lattice version of Kohn-Luttinger physics, despite that the pairing symmetries are different. I discuss under what conditions the pairing occurs and rationalize the need to do renormalization-group studies. I also discuss the interplay between superconductivity and density-wave instabilities.
Tuesday, February 7, 2017
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
Metal joining is a controlled process used to fuse metals. There are several techniques of metal joining of which friction stir welding is one of the more basic forms. Friction stir welding is an innovative weld process that continues to grow in use, in the commercial, defense, and space sectors. It produces high quality and high strength welds in aluminum alloys. The process consists of a rotating weld pin tool that plasticizes material through friction. The plasticized material is welded by applying a high weld forge force through the weld pin tool against the material during pin tool rotation. Self-reacting friction stir welding (SR-FSW) is one variation of the FSW process developed at the National Aeronautics and Space Administration (NASA) for use in the fabrication of propellant tanks and other areas used on the Space Launch System (SLS)
NASA's SLS is an advanced, heavy-lift launch vehicle which will provide an entirely new capability for science and human exploration beyond Earth's orbit. The SLS will give the nation a safe, affordable and sustainable means of reaching beyond our current limits and open new doors of discovery from the unique vantage point of space.
Wednesday, February 1, 2017
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
In this talk, I will focus on cosmologies that replace the big bang with a big bounce. I will explain how, in these scenarios, the large-scale structure of the universe is determined during a contracting phase before the bounce and will describe the recent development of the first well-behaved classical (non-singular) cosmological bounce solutions.
Wednesday, January 18, 2017
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
"Searching for Dark Matter in Gravitational Waves"
Ilias Cholis , Johns Hopkins University
[Host: Peter Arnold]
The nature of dark matter is one of the most longstanding and puzzling questions in physics. With cosmological measurements we have been able to measure its abundance with great precision. Yet, what dark matter is composed of remains a mystery.
In 2016 the first ever observation of gravitational waves from the coalescence event of two black holes was achieved by the LIGO interferometers.
Together with my collaborators we recently advocated that the interactions of 30 solar masses primordial black holes composing the dark matter could explain this event.
This opens up a new window in indirect searches for dark matter.
In my talk, I will discuss the various probes to distinguish between these mergers of primordial black holes, from the more traditional astrophysical black hole binaries.
One is through their mass spectrum, another is through cross-correlation of gravitational events with future overlapping galaxy catalogs. A third, is through their contribution to the stochastic gravitational wave background. Finally a fourth probe uses the fact that primordial black black holes form binaries with highly eccentric orbits. Those will then merge on timescales that in some cases are years, days or even minutes, retaining some eccentricity in the last seconds before the merger, which can be detected by LIGO and future ground based interferometers.
Graphene in its pristine form has transformed our understanding of 2D electron systems leading to fundamental discoveries and to the promise of important applications. I will discuss new and surprising phenomena that emerge when the perfect honeycomb lattice of graphene is disrupted. In particular I will focus on the effects of single atom vacancies on graphene's electronic and magnetic properties as revealed by scanning tunneling microscopy and spectroscopy. These include charging the vacancy site into the supercritical regime where we observe the formation of an artificial 2D atom 1, and electrostatically controlled Kondo screening of the vacancy magnetic moment.
1 J.Mao, Y.Jiang, D. Moldovan, G. Li, K. Watanabe, T. Taniguchi, M. R. Masir, F.M. Peeters, E.Y. Andrei, Tunable Artificial Atom at a Supercritically Charged Vacancy in Graphene, Nature Physics 2016, doi:10.1038/nphys3665
Friday, November 18, 2016
3:30 PM
Physics Building, Room 203
Note special room.
DES is an ongoing imaging sky survey, the largest such survey to date. Its main science goal is to shed light onto dark energy by making precision measurements of the expansion history and growth of structure in the universe. In this talk I present an overview of our latest results and introduce a new DES initiative: searches for optical counterparts to gravitational wave events.
A public lecture by Adam Reiss, recipient of the 2011 Nobel Prize for the detection of the accelerating expansion of the universe using distant supernovas. The lecture will be presented at 7 pm on Wednesday, November 9, at the Paramount Theater on Charlottesville's Downtown Mall.
The Physics and Astronomy Departments at the University of Virginia in partnership the National Radio Astronomy Observatory invite the community to a special FREE public lecture by Nobel Laureate Adam Riess at The Paramount Theater on Wednesday, November 9 at 7:00PM. Prof. Riess will speak on the fascinating topic of the accelerating universe. Due to his critical contributions, Prof. Riess shared the 2011 Nobel Prize "for the discovery of the accelerating expansion of the Universe through observations of distant supernovae." The term "supernovae" refers to stars exploding at the end of their lives. The team Prof. Riess worked with used a particular kind of supernova, called type Ia supernova, to understand the properties of distant galaxies. His research team found that light from distant supernovae was weaker than expected ‐ this was a sign that the expansion of the Universe was accelerating. Prof. Riess will discuss the excitement of this discovery, its implications, and current ongoing work to help answer remaining questions.
Friday, September 30, 2016
3:30 PM
Physics Building, Room 204
Note special room.
Some 40 years ago Hawking found a remarkable contradiction: if we accept the standard behavior of gravity in regions of low curvature, then the evolution of black holes will violate quantum mechanics. Resolving this paradox would require a basic change in our understanding of spacetime and/or quantum theory. This paradox has found an interesting resolution through string theory. While quantum gravity is normally expected to be important only at distances of order planck length, the situation changes when a large number N of particles are involved, as for instance in the situation where we make a large black hole. Then the length scale of quantum gravity effects grows with N, altering the black hole structure to a "fuzzball"; this effect resolves the paradox.
Friday, September 23, 2016
3:30 PM
Physics Building, Room 204
Note special room.
An objective overview of the nuclear arms race will be presented with an emphasis on the present situation. A brief sketch of how nuclear weapons work and some ironic lessons from history will be presented. Scientists' discussions about preventing proliferation and use started in the secrecy of the Manhattan Project and continued in public during the rapid cold war buildup to the present (e.g., Bulletin of the Atomic Scientists). The central role of the nuclear non-proliferation treaty, the Iran agreement, possible pathways to nuclear conflict, and a personal view of the outlook to prevent future nuclear weapons use, including the vital role of education, will be presented.
Aron Bernstein is Professor of Physics, Emeritus, MIT. His physics research has focused on experimental tests of the symmetries of the standard model (chiral anomaly and symmetry). He has followed the nuclear arms race carefully since the Cuban Missile Crisis, has taught courses on this subject, and has done research on arms control issues such as the dangers posed by the Russian and US short ballistic missile launch and warning times. He is a National Board Member of the Council for a Livable World, started by physicist Leo Szilard, which works with Congress on nuclear arms control issues.
"Electron Circular Dichroism and the Origin of Life On Earth"
Tim Gay , University of Nebraska
[Host: Xiaochao Zheng]
We have bombarded chiral halocamphor molecules in the gas phase with low-energy (< 1 eV), longitudinally-spin-polarized electrons, and investigated dissociative electron attachment (DEA) reactions:
e- + HA → H- + A,
where H is a halogen atom (Br or I) and A is the residual camphor fragment. We observe that for a given target handedness, the total DEA cross section depends on the helicity of the incident electron. In the case of iodocamphor at the lowest incident electron energies, this effect can be as large as two parts in 1000. The observation of chiral sensitivity in a break-up reaction is important because, among other things, it validates the premise of the Vester-Ulbricht hypothesis regarding the origins of biological homochirality. The sordid history of previous attempts to demonstrate such effects will be briefly reviewed.
Monday, May 2, 2016
3:30 PM
Physics Building, Room 203
Note special date.
Note special room.
"The Remarkable Story of LIGO's Detection of Gravitational Waves"
Peter Shawhan , University of Maryland
[Host: Peter Arnold]
On February 11, LIGO scientists announced the direct detection of gravitational waves, confirming a century-old prediction of Einstein's general theory of relativity. This milestone was finally made possible with the incredibly sensitive Advanced LIGO detectors, combined with a certain measure of luck. This first event is already enough to investigate the properties of the source, test the theory of gravity, and project what more we can learn from future events. I will share both the scientific meaning of the discovery and some of the personal stories behind it.
Friday, April 29, 2016
3:30 PM
Physics Building, Room 204
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"30 years of high Tc: Superfluid and normal-fluid densities in the cuprate superconductors"
David Tanner , University of Florida
[Host: Seunghun Lee]
It was in April 1986 when Bednorz and Mueller of the IBM Zürich laboratories sent a paper about “possible high-Tc superconductivity” to Zeitschrift für Physik B. The resulting bombshell changed condensed-matter physics forever. Experimenters and theorists developed methods to measure and calculate in ways that were much improved over prior years. However, despite 30 years of intense study, the description of these materials remains incomplete. I’ll discuss the discovery of the high Tc cuprates from the perspective of a participant. I’ll then turn to what infrared spectroscopy can tell us about their properties. Measurements for a number of cuprate families of optical reflectance over a wide spectral range (far-infrared to ultraviolet) have been analyzed using Kramers-Kronig analysis to obtain the optical conductivity, s(w), and (by integration of the real part of the conductivity) the spectral weight of low- and mid-energy excitations. For the Kramers-Kronig analysis to give reliable results, accurate high-frequency extrapolations, based on x-ray atomic scattering functions, were used. When the optical conductivities of the normal and superconducting states are compared, a transfer of spectral weight from finite frequencies to the zero-frequency delta-function conductivity of the superconductor is seen. The strength of this delta function gives the superfluid density, rs. There are two ways to measure rs, using either the low energy spectral weight or by examination of the imaginary part, s2(w); both estimates show that 98% of the ab-plane superfluid density comes from low energy scales, below about 0.15 eV. Moreover, there is a notable difference between clean metallic superconductors and the cuprates. In the former, the superfluid density is essentially equal to the conduction electron density. The cuprates, in contrast, have only about 20% of the ab-plane low-energy spectral weight in the superfluid. The rest remains in finite-frequency, midinfrared absorption. In underdoped materials the superfluid fraction is even smaller. The consequences of this observation for the electronic structure will be addressed.
Friday, April 22, 2016
3:30 PM
Physics Building, Room 204
Note special room.
"How many electrons make a semiconductor nanocrystal film metallic? "
Boris Shklovskii , Univ. Minnesota
[Host: Eugene Kolomeisky]
Films of semiconductor nanocrystals are used as a novel, low-cost electronic materials for optoelectronic devices. To achieve their full potential a better understanding of their conductivity as a function of concentration of donors is required. So far, it is not known how many donors will make a nanocrystal film metallic. In bulk semiconductors, the critical concentration of electrons at the metal-insulator transition is universally described by the famous Mott criterion. We show theoretically that in a dense NC film, where NCs touch each other by small facets with radius r << d, the critical concentration of electrons N at the metal-insulator transition satisfies the condition is given by N r^3 = 1.
This critical concentration is typically 100 times larger than the Mott one. In the accompanying experiments, we investigate the conduction mechanism in films of phosphorus-doped silicon nano-crystals. At the largest electron concentration achieved in our samples, which is half the predicted N, we find that the localization length of hopping electrons is close to three times the nano-crystals diameter, indicating that the film approaches the metal-insulator transition.
Friday, April 15, 2016
3:30 PM
Physics Building, Room 204
Note special room.
"How to Understand Molecular Transport through Channels: The Role of Interactions"
Anatoly Kolomeisky , Rice University
[Host: Israel Klich ]
The motion of molecules across channels and pores is critically important for understanding mechanisms of many biological, chemical, physical and industrial processes. Here we investigate the role of different types of interactions in the channel-facilitated molecular transport by analyzing exactly solvable discrete-state stochastic models. According to this approach, the channel transport is a non-equilibrium process that can be viewed as a set of coupled quasi-chemical transitions between discrete spatially separated states. It allows us to obtain a full dynamic description of the translocation via the pore, clarifying many aspects of these complex processes. We show that the strength and the spatial distribution of the molecule/channel interactions can strongly modify the particle fluxes through the system. Our analysis indicates that the most optimal transport is achieved when the binding sites are near the entrance or near the exit of the pore, depending on the sign of the interaction potentials. These observations allow us to explain current single-molecule experiments on the translocation of polypeptides through biological channels. We also suggest that the intermolecular interactions during the channel transport might significantly influence the overall translocation dynamics. Our explicit calculations show that the increase in the flux can be observed for some optimal interaction strengths. But the flux can also be fully suppressed for some conditions. The relevance of these results for biological systems is discussed. The physical-chemical mechanisms of these phenomena are analyzed from the microscopic point of view.
Thursday, April 14, 2016
7:00 PM
Chemistry Building, Room 402
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"Impact and Intrusion: the surprises and elegance of how nature arranges the texture of our lives"
Sidney R. Nagel , University of Chicago
[Host: Seunghun Lee]
Many complex phenomena are so familiar that we hardly realize that they defy our normal intuition. Examples include the anomalous flow of granular material, the long messy tendrils left by honey spooned from one dish to another, the pesky rings deposited by spilled coffee on a table after the liquid evaporates or the common splash of a drop of liquid onto a countertop. Aside from being uncommonly beautiful to see, many of these phenomena involve non-linear behavior where the system is far from equilibrium. Although most of the world we know is beyond description by equilibrium theories, we are still only at the threshold of learning how to deal with such deep and complex behavior. Thus, these are phenomena that can lead the inquisitive into new realms of physics.
Friday, April 8, 2016
3:30 PM
Physics Building, Room 204
Note special room.
"Seeds of Supermassive Black Holes at High Redshifts"
Isaac Shlosman , University of Kentucky
[Host: Eugene Kolomeisky]
Detection of distant quasars at redshifts of ~6-7 provides a challenge to the standard picture of structure formation in the universe within the hierarchical framework, as the universe is less than a Gigayear old at this time. What are seeds of supermassive black holes (SMBHs) that power these luminous objects? After all, massive objects should form late in the evolution ... Did SMBHs form as a result of stellar evolution? In my talk, I will address various aspects of this problem and discuss viable and emerging alternatives to this paradigm.
Friday, April 1, 2016
3:30 PM
Physics Building, Room 204
Note special room.
"Do Electrons in a Metal Have the Same Charge as Free Electrons in Vacuum?"
Neil Zimmerman , NIST
[Host: Jongsoo Yoon]
At NIST, we have the enjoyable jobs of combining i) state-of-the-art research with ii) the fascinating search for higher and higher accuracy measurements. In this talk, I will i) introduce the SI system of units and explain why devices that can move around single electrons one-by-one are of great interest, ii) give an introduction to the nanoelectronic devices known as single electron transistors and pumps, iii) describe a high-accuracy measurements of the charge of electrons in a metal, and iv) discuss the possibility that this charge is not the same as the charge of a free electron in vacuum.
Thursday, March 31, 2016
9:45 AM
Wilsdorf Hall, Room 200
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Note special time.
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"Opportunities for Collaboration at Oak Ridge National Laboratory"
Ian Anderson , ORNL
[Host: Despina Louca]
Friday, March 25, 2016
3:30 PM
Physics Building, Room 204
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"Golden Era of Modern Magnetism "
Prof. Chia Ling Chien , Johns Hopkins University
[Host: Seunghun Lee]
Magnetism has been an old subject dating back to antiquity. Few could envision that modern magnetism would enter a golden era with the realization of so many new phenomena and game-changing technologies. These remarkable advances are due to spin ½ of electrons, as illustrated in this talk through several recent examples, including pure spin current phenomena, skyrmion materials, and p-wave superconductivity.
Thursday, March 24, 2016
7:30 PM
Maury Hall, Room 209
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"Rediscovering Pluto: a panel on NASA's recent Pluto Mission (New Horizons)"
Alice Bowman and Anne Verbiscer
[Host: UVA Physics and Astronomy Departments]
On July 14, 2015, New Horizons, an interplanetary space probe, flew by Pluto, capturing the first high resolution photographs of Pluto’s surface and atmosphere. New Horizons data has revealed stunning geology including ice volcanoes, Nitrogen ice glaciers, mysterious internal heating, and the “snakeskin” patterns among 50 other discoveries. UVA’s planetary astronomer, Anne Verbiscer, will describe Pluto’s amazing science phenomena, and Alice Bowman will explain the missions and engineering side of New Horizons sharing her experience as New Horizons’ MOM. This event is meant for the general public, and everyone is invited. A reception will follow the talk.
Sponsored by UVA Physics and Astronomy Departments.
Organized by Astronomical Society at UVA and SPS
A map showing the location of Maury Hall is available online at the following address:
http://www.virginia.edu/webmap/popPages/55-MauryHall.html
Friday, March 18, 2016
3:30 PM
Physics Building, Room 204
Note special room.
"Atom Interferometry Measurements of Atomic Polarizabilities and Tune-out Wavelengths"
Alex Cronin , University of Arizona
[Host: Cass Sackett]
Atom interferometry, in which de Broglie waves of matter are coherently split and later recombined to make interference fringes, is a precision measurement method with applications in many fields of physics. In Arizona, we measured the ground-state static electric-dipole polarizabilities of Cs, Rb, and K atoms with 0.2% uncertainty using an atom beam interferometer. We also measured a tune-out wavelength for K atoms with sub-picometer uncertainty. I will discuss how these experiments use electric field gradients to induce polarizability-dependent phase shifts for atomic de Broglie waves. Our measurements provide benchmark tests for atomic structure calculations and thus test the underlying theory used to predict van der Waals forces and to interpret atomic parity non-conservation experiments.
Friday, March 4, 2016
3:30 PM
Physics Building, Room 204
Note special room.
Machine Learning (statistical engineering) capabilities are in a phase of tremendous growth. Underlying these advances is a strong and deep connection to various aspects of statistical physics. There is also a great opportunity in pointing these tools toward physical modeling. In this colloquium I illustrate the two-way flow of ideas between physics and statistical engineering on three examples from our team LANL. First, I review the work on structure learning and statistical estimation in power system distribution (thus physical) networks. Then I describe recent progress in constructive understanding of graph learning (on example of inverse Ising model) illustrating that the generic inverse task (of learning) is computationally easy in spite of the fact that the direct problem (inference or sampling) is difficult. I conclude speculating how macro-scale models of physics (e.g. large eddy simulations of turbulence) can be learned from micro-scale simulations (e.g. of Navier-Stocks equations).
Friday, February 19, 2016
3:30 PM
Physics Building, Room 204
Note special room.
"Metamagnetism - its ubiquity and universality"
Bellave Shivaram , University of Virginia - Physics Dept.
[Host: Vittorio Celli]
The emergent universality in the nonlinear magnetic response of itinerant metamagnets will be discussed. Recent experimental work on heavy fermions, Hunds metals, and single molecule magnets will be presented. The appeal of the ‘single energy scale model’ developed in the context of these new measurements [(a) "Universality in the Nonlinear Magnetic Response of Strongly Correlated Metals", B.S. Shivaram, D.G. Hinks, M.B. Maple and P. Kumar, Phys. Rev., B89, 241107(Rapid Communication), 2014. [b] "Metamagnetism and the Fifth Order Susceptibility in UPt3", B.S. Shivaram, Brian Dorsey, D.G. Hinks and Pradeep Kumar, Phys. Rev., B89, 161108(Rapid Communication), (2014). [c] “High Field Ultrasound Measurements in UPt3 and the Single Energy Scale Model of Metamagnetism”, B.S. Shivaram, V.W. Ulrich, P. Kumar and V. Celli, Phys. Rev.B, 91, 115110, 2015] will be critically examined.
Friday, February 12, 2016
3:30 PM
Physics Building, Room 204
Note special room.
"Tailoring properties of single and bilayer layer transition metal dichalcogenides: looking beyond graphene*"
Talat Rahman , University of Central Florida
[Host: Vittorio Celli]
Single-layer of molybdenum disulfide (MoS2) and other transition metal dichalcogenides appear to be promising materials for next generation nanoscale applications (optoelectronic and catalysis), because of their low-dimensionality, intrinsic direct band-gap which typically lies in the visible spectrum, and strikingly large binding energies for excitons and trions. Several experimental groups have already reported novel electronic and transport properties which place these material beyond graphene for device applications. MoS2 is also known to be a leading hydrodesulphurization catalyst. Efforts are underway to further tune these properties through alloying, defects, doping, coupling to a substrate, and formation of bilayer stacks (homo- and hetero-structures). In this talk I will present results [1-3] which provide a framework for manipulating the functionality of these fascinating materials and take us closer to the goal of rational material design. My emphasis will be on properties of pure and defect-laden single layer MoS2 with and without underlying support. I will also provide rationale for the differences in the excitation energetics and ultrafast charge dynamics in single and bilayer (hetero and homo) dichalcogenides.
[1] D. Sun, et al., “An MoSx Structure with High Affinity for Adsorbate Interaction,” Angew. Chem. Int. Ed. 51, 10284 (2012).
[2] D. Le, T. B. Rawal, and T. S. Rahman, “Single-Layer MoS2 with Sulfur-Vacancies: Structure and Catalytic Application,” J. Phys. Chem. C 118, 5346 (2014).
[3] A. Ramirez-Torres, V.Turkowski, and T. S. Rahman, “Time-dependent density-matrix functional theory for trion excitations: application to monolayer MoS2,” Phys. Rev. B 90, 085419 (2014).
I will review the basic underlying science of climate and climate change, including physically-based models of Earth's climate. I will motivate the use of a simple, zero-dimensional "Energy Balance Model" of Earth's radiative balance that can be used to estimate the global mean surface temperature of Earth. I will show how this model successfully reproduces the observed historical changes in global temperature, and how it can be used to assess various questions about future human-caused climate change.
Friday, January 29, 2016
3:30 PM
Physics Building, Room 204
Note special room.
"Things that go bump in the data: QCD Puzzles, Predictions, and Prognoses"
Fred Olness , Southern Methodist University
[Host: Simonetta Liuti]
The very successful Run I of the Large Hadron Collider (LHC) culminated in the discovery of the Higgs boson which was the subject of the 2013 Nobel Prize.
How will we know if there are other "undiscovered" particles in the data? (And, was there a hint from CERN last month???) This will require improved calculations, and the key ingredients are:
i) higher-order theoretical cross section calculations, and
ii) precise Parton Distribution Functions (PDFs) that characterize the proton structure.
Surprisingly, these predictions are influenced by a wide range of data including precision low-energy nuclear results. Recent theoretical developments improve our ability to address the QCD multi-scale problem and higher orders across the full kinematic range.
We look at some of the topics, puzzles, and challenges that lie on the horizon, and identify areas where additional efforts are required.
Friday, January 22, 2016
3:30 PM
Physics Building, Room 204
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"Building a quantum computer from the top down: massive-scale entanglement in the quantum optical frequency comb"
Olivier Pfister , UVA-Physics
[Host: Seunghun Lee]
Quantum computing offers revolutionary promises of scientific and societal importance, based on its exponential speedup of particular tasks: on the one hand, Richard Feynman's quantum simulator would allow us to tackle currently intractable quantum chemistry problems (nitrogen fixation, carbon sequestration) as well as quantum physics ones (high-Tc superconductivity); on the other hand, Peter Shor's algorithm for factoring integers would render RSA encryption obsolete.
Building a practical quantum computer demands that one address the challenges of decoherence and scalability. While the platforms of trapped-ion qubits and of superconducting qubits have made spectacular progress in the fight against decoherence, our approach has been to tackle scalability, in particular by discovering a new “top down,” rather than “bottom up,” method for generating the entangled states, or "cluster" states, that enable the particular flavor of quantum computing called measurement-based, or one-way, quantum computing.
Our method uses the continuous variables of light — “qumodes,” rather than qubits — defined by the quadrature amplitudes of the quantized electromagnetic field emitted over the cavity modes, or quantum optical frequency comb, of a single optical parametric oscillator. We demonstrated a world-record cluster state size of 60 entangled qumodes (3 × 103 in progress), all simultaneously available in the frequency domain. I will also present our new proposal for generating cluster states of unlimited size by using both the time and frequency degrees of freedom.
Friday, December 4, 2015
3:30 PM
Physics Building, Room 204
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"Spatial Imaging of Quarks and Gluons in the Proton"
Charles Hyde , Old Dominion University
[Host: Simonetta Liuti]
For many years, it was generally thought that spatial imaging of the proton was impossible in principle, due to the relativistic recoil of the proton when ever it is probed at momentum scales of order of the inverse of the proton size. Two decades ago, a new set of QCD matrix elements were defined, called Generalized Parton Distributions (GPDs), that encode the spatial distributions of quarks and gluons transverse to a preferred momentum axis. It was independently discovered that the GPDs are accessible experimentally in Deep Virtual Exclusive reactions: high energy reactions of the type e p —> e p gamma.
I will review the progress of experimental efforts to measure GPDs, and discuss the extent to which spatial distributions can be extracted from present and future data.
Friday, November 20, 2015
3:30 PM
Physics Building, Room 204
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"Discovery of Electron Neutrino Appearance from a Muon Neutrino Beam in T2K and Future Outlook for Discovery of CP Violation in Lepton Sector in DUNE at LBNF"
Chang Kee Jung , SUNY at Stony Brook
[Host: Seunghun Lee]
Matter-antimatter asymmetry is one of the most outstanding mysteries of the universe that provides a necessary condition to our own existence. There have been various attempts to solve this mystery including 'Baryogenesis' hypothesis. However, the B-factory experiments during the last decade showed that the observed CP-violation (CPV) in the quark sector is not big enough for baryogenesis to be a viable solution to the matter-antimatter asymmetry. This leads us to the 'Leptogenesis' hypothesis, in which CPV in the lepton section plays a crtical role to create the matter-antimater asymmetry at the onset of the Big Bang. Thus, experimental observation of CPV in the lepton sector could prove to be tantamount to one of the most important discoveries in our understanding of the universe.
In 2011, the T2K experiment published a result that provided the first indication for a non-zero $\theta_{13}$, the last unknown mixing angle in the lepton sector at that time, at 2.5 sigma level of significance. In 2013, after analyzing two more years of data taken since 2011, the experiment reported "Observation of electron neutrino appearance from a muon neutrino beam" at 7.3 sigma level of significance. While neutrino oscillation has been well-established since the discovery by the Super-Kamiokande experiment in 1998, there have not been a definitive observation of neutrino oscillation in a so-called "appearance mode", and this new T2K observation is the first time an explicit neutrino flavor (electron) appearance is observed from another neutrino flavor (muon). This observation also opens the door to study CPV in neutrinos. When incorporating recent precision measurements on $\theta_{13}$ by the reactor experiments along with other neutrino oscillation parameter measurements, T2K data show an intriguing initial result on the $\delta_{CP}$, which is further corroborated by the Super-Kamiokande atmospheric neutrino results as well as the most recent results from NOvA.
Ultimately, however, in order to establish unequivocal results on leptonic CPV, we need a next generation experiment with a more powerful beam, and a larger and/or higher resolution detector. The Deep Underground Neutrino Experiment (DUNE) in US that is newly established as a truly international collaboration, is such an experiment. Physics goals of DUNE include: discovery of CPV in the lepton sector, detrmination of mass hierarchy, discovery of proton decay and observation of neutrinos from the Type-II supernovae. In this talk I will introduce the rapidly developing DUNE experiment and the collaboration, and also discuss possible opportunities for participation.
I will also briefly comment on the Nobel Prize in Physics 2015 as well as The Breakthrough Prize in Fundamental Physics 2016 that were given to the
neutrino oscillation experiments.
Friday, November 13, 2015
3:30 PM
Physics Building, Room 204
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"Friction, magnetism and superconductivity: Are they interrelated?"
Jackie Krim , North Carolina State University
[Host: Joe Poon]
Studies of the fundamental origins of friction have undergone rapid progress in recent years with the development of new experimental and computational techniques for measuring and simulating friction at atomic length and time scales. The increased interest has sparked a variety of discussions and debates concerning the nature of the atomic-scale and quantum mechanisms that dominate the dissipative process by which mechanical energy is transformed into heat. Measurements of the sliding friction of physisorbed monolayers and bilayers in gaseous and liquid enviroments provide information on the relative contributions of electronic, magnetic, electrostatic and phononic dissipative mechanisms. The experiments will be discussed within the context of current theories of how friction originates at the atomic scale.
Friday, October 30, 2015
3:30 PM
Physics Building, Room 204
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"A “Rough” View of Friction and Adhesion"
Mark Robbins , Johns Hopkins University
[Host: Seunghun Lee]
Friction affects many aspects of everyday life and has played a central role in technology dating from the creation of fire by rubbing sticks together to current efforts to make nanodevices with moving parts. The friction "laws" we teach today date from empirical relationships observed by da Vinci and Amontons centuries ago. However, understanding the microscopic origins of these laws remains a challenge. While Amontons said area was proportional to load and independent of area, most modern treatments assume that friction is proportional to the real area of contact where atoms on opposing surfaces are close enough to repel. Calculating this area is complicated because elastic interactions are long range and surfaces are rough on a wide range of scales. In many cases they can be described as self-affine fractals from nanometer to millimeter scales. The talk will first show that this complex problem has a simple solution. Dimensional analysis implies a linear relation between real contact area and load that can explain both Amontons' laws and many exceptions to them. Next the talk will explain why we can't climb walls like spiderman even though the attractive interactions between atoms on our finger tips should provide enough force to support our weight. The talk will conclude by considering how forces in the contact area give rise to friction. Friction shows surprisingly counterintuitive and complex behavior in nanometer to micrometer scale contacts and only a few explanations are consistent with macroscopic measurements.
Friday, October 23, 2015
3:30 PM
Physics Building, Room 204
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"Broadband Molecular Rotational Spectroscopy for Chemical Dynamics and Molecular Structure"
Brooks Pate , UVA - Chemistry
[Host: Thomas Gallagher]
Until about 2005, molecular rotational spectroscopy was performed using narrowband (~1 MHz) excitation of a low-pressure gas in a resonant cavity. This method offers high sensitivity for each data acquisition, but the time required to perform a spectrum scan over about 10 GHz, needed to capture the rotational spectrum, was a major limitation to applications of the technique. Advances in high-speed digital electronics have made it possible to design spectrometers that offer instantaneous, broadband (> 10 GHz) performance. During our initial work with high-speed arbitrary waveform generators and digitizers (with Tom Gallagher) we developed the method of chirped pulse Fourier transform rotational spectroscopy that uses a pulse with linear chirp to phase-reproducibly excite the gas sample. The subsequent coherent emission (free induction decay) is detected with the high-speed digitizer and the frequency domain spectrum is obtained using FFT analysis. Since the introduction of the technique in 2008 [1], the method has been applied to unimolecular reaction dynamics [2], the structures of molecular clusters [3], and the laboratory identification of molecules in the interstellar medium [4]. The technique has been extended to mm-wave spectroscopy with applications to Rydberg spectroscopy [5], chemical reaction dynamics, and analytical chemistry. The broadband technique has also enabled a new generation of molecular structure studies in the field of chirality [6] with the potential for solving significant challenges for real-time pharmaceutical manufacturing.
References
[1] G.G. Brown, B.C. Dian, K.O. Douglass, S.M. Geyer, and B.H. Pate, “A Broadband Fourier Transform Microwave Spectrometer Based on Chirped Pulse Excitation” Rev. Sci. Instrum. 79, 053103 (2008).
[2] B.C. Dian, G.G. Brown, K.O. Douglass, and B.H. Pate, “Measuring Picosecond Isomerization Dynamics via Ultra-broadband Fourier Transform Microwave Spectroscopy”, Science 320, 924-928 (2008).
[3] C. Pérez, M.T. Muckle, D.P. Zaleski, N.A. Seifert, B. Temelso, G.C. Shields, Z. Kisiel, and B.H. Pate, “Structures of Cage, Prism, and Book Isomers of Water Hexamer from Broadband Rotational Spectroscopy”, Science 336, 897-901 (2012).
[4] D.P. Zaleski, N.A. Seifert, A.L. Steber, M.T. Muckle, R.A. Loomis, J.F. Corby, O. Martinez, Jr., K.N. Crabtree, P.R. Jewell, J.M. Hollis, F.J. Lovas, D. Vasquez, J. Nyiramahirwe, N. Sciortino, K. Johnson, M.C. McCarthy, A.J. Remijan, and B.H. Pate, “Detection of E-cyanomethanimine towards Sagittarius B2(N) in the Green Bank Telescope PRIMOS Survey”, Ap. J. Letters, 765, L10 (2013).
[5] K. Prozument, A.P. Colombo, Y. Zhou, G.B. Park, V.S. Petrovic, S.L. Coy, and R.W. Field, “Chirped-pulse Millimeter-wave Spectroscopy of Rydberg-Rydberg Transitions”, Phys. Rev. Lett. 107, 143001 (2011).
[6] D. Patterson, M. Schnell, and J.M. Doyle, “Enantiomer-specific detection of chiral molecules via microwave spectroscopy”, Nature 497, 475 (2013).
Friday, October 16, 2015
3:30 PM
Physics Building, Room 204
Note special room.
"Surfing on a Plasma Wave - Can a Grand Challenge for Engineering Answer the Big Questions of Physics?"
Thomas Katsouleas , Provost and Department of Physics UVA
[Host: Joseph Poon]
The National Academy of Engineering has identified 14 Grand Challenges for Engineering for the 21st Century, spanning human needs from sustainability to security, health and joy of living. The last category includes such topics as engineering the tools of scientific discovery. This talk will include a brief review of the NAE Grand Challenges and the response of higher education to the Challenges, and will conclude with a review of one Grand Challenge topic: the development of ultra-compact particle accelerators based on surfing at (nearly) the speed of light on waves created by lasers or particle beams in a plasma gas. The prospects of these devices as tools of scientific discovery as well as beam therapy will be discussed.
Friday, September 25, 2015
3:15 PM
Physics Building, Room 204
Note special time.
Note special room.
"Iron Chef: recipes for building magnetic structures atom by atom"
Adrian Feiguin , Northeastern University
[Host: Israel Klich ]
Understanding Magnetism is a complex undertaking: it relies on our knowledge of the exact position of magnetic ions in a crystal and their interactions. More important, at its core, this is fundamentally a quantum problem and requires understanding the cooperative effects of many degrees of freedom. In the past decade, we have witnessed enormous progress in experiments that consist of placing magnetic atoms at predetermined positions on substrates, and building magnetic nanostructures, one atom at a time. The electrons in the substrate mediate the interactions between the spins, and scanning tunneling microscopy allows one to study their properties.
In order to understand these interactions, we rely on a theory developed decades ago by Ruderman, Kittel, Kasuya, and Yosida, dubbed "RKKY Theory", which applies when the spins are classical. The quantum nature of the electronic spin introduces more complexity, and competition with another quantum phenomena: the Kondo effect. The combined effect is non-trivial, and can only be studied by numerical means. I will describe this effect by introducing an exact mapping onto an effective one-dimensional problem that we can solve with the density matrix renormalization group method (DMRG). I will also show that for dimension d>1, Kondo physics dominates even at short distances, while the ferromagnetic RKKY state is energetically unfavorable. This may have important implications for our understanding of heavy fermion materials and magnetic semiconductors.
Friday, September 18, 2015
3:30 PM
Physics Building, Room 204
Note special room.
I will review the current status of the Mu2e and NOvA experiments at Fermilab. These experiments hope to shed light on several important topics in particle physics: neutrino oscillations, lepton flavor, the matter/antimatter asymmetry of the Universe, dark matter, and others. As I describe the status and goals of these experiments I will highlight the impact of our UVA efforts.
Friday, September 11, 2015
3:30 PM
Physics Building, Room 204
Note special room.
When magnetic moments are interacting with each other in a situation resembling that of complex love triangles, called frustration, a large set of states that are energetically equivalent emerge. This leads to exotic spin states such as spin liquid and spin ice. In their paper recently published in the Proceedings of the National Academy of Sciences (PNAS), we presented evidence for the existence of a topological glassy state, that we call a spin jam, induced by quantum fluctuations. The case in point is SrCr9pGa12-9pO19 (SCGO(p)), a highly frustrated magnet, in which the magnetic Cr ions form a quasi-two-dimensional triangular system of bi-pyramids. This system has been an archetype in search for exotic spin states. Understanding the nature of the state has been a great intellectual challenge. Our new experimental data and theoretical spin jam model provide for the first time a coherent understanding of the phenomenon. Furthermore, the findings strongly support the possible existence of purely topological glassy states.
Monday, April 27, 2015
3:30 PM
Physics Building, Room 203
Note special date.
Note special room.
"The Novel World of Hadron Physics"
Stanley J. Brodsky , SLAC, Stanford University
[Host: Dinko Pocanic]
I will survey a number of exciting new developments in hadron physics.
These include: new insights into the nature of the color-confining confinement quark potential in quantum chromodynamics; a novel application of supersymmetry to hadron physics; the relation between the parameter ΛMS
which controls high-energy interactions of quarks to the mass of the proton; and the elimination of the renormalization scale ambiguity for perturbative QCD calculations.
I will also discuss several novel experimental tests of QCD which can be performed at JLab, including: hard exclusive and diffractive reactions, flavor-dependent antishadowing of nuclear interactions; intrinsic strange- and charm-quark phenomena; the production of tetraquarks and other exotic hadronic states; and factorization-breaking lensing phenomena.
Friday, April 24, 2015
3:30 PM
Physics Building, Room 204
Note special room.
"Ultracold molecules – a new frontier for quantum physics and chemistry"
Jun Ye , JILA, National Institute of Standards and Technology, University of Colorado
[Host: Olivier Pfister]
Molecules cooled to ultralow temperatures provide fundamental new insights to strongly correlated quantum systems, molecular interactions and chemistry in the quantum regime, and precision measurement. Complete control of molecular interactions by producing a molecular gas at very low entropy and near absolute zero has long been hindered by their complex energy level structure. Recently, a range of scientific tools have been developed to enable the production of molecules in the quantum regime. Here, molecular collisions follow full quantum descriptions. Chemical reaction is controlled via quantum statistics of the molecules, along with dipolar effects. Further, molecules can be confined in reduced spatial dimensions and their interactions precisely manipulated via external electromagnetic fields. For example, by encoding a spin-1/2 system in rotational states, we realize a spin lattice system where many-body spin dynamics are directly controlled by long-range and anisotropic dipolar interactions. These new capabilities promise further explorations of strongly interacting and collective quantum effects in exotic quantum matter.
Inflationary cosmology gives a plausible explanation for many observed features of the universe, including its uniformity, its mass density, and the patterns of the ripples that are observed in the cosmic microwave background. Beyond what we can observe, most versions of inflation imply that our universe is not unique, but is part of a possibly infinite multiverse. I will describe the workings of inflation, the evidence for inflation, and why I believe that the possibility of a multiverse should be taken seriously.
Friday, April 10, 2015
3:30 PM
Physics Building, Room 204
Note special room.
"Engaging with DPRK for Science Diplomacy and World Peace"
ChanMo Park , Chancellor of PUST/Former President of POSTECH
[Host: Seunghun Lee]
As Chancellor of the Pyongyang University of Science & Technology (PUST) starting in October, 2010, I have seen the slow changes in DPRK, especially after Kim Jong Un took over the power in January, 2012. Globalizing DPRK is essential for peaceful coexistence and eventual reunification of two Koreas. One way to achieve this goal is Science Diplomacy, in particular educating young talents and globalizing them.
In this colloquium, a brief introduction about collaborative activities in science and technology between South and North Koreas will be presented, followed by more extensive presentation about the history and current status of PUST. And then the globalization efforts of PUST will be presented, to show that the PUST students are being internationalized and it is hoped that they will globalize their country in the near future, which will make an important contribution to the World Peace.
Friday, April 3, 2015
3:30 PM
Physics Building, Room 204
Note special room.
"Discovering Ultra-High Energy Cosmic Rays with your Smartphone"
Mike Mulhearn , UC Davis
[Host: Bob Hirosky]
Cosmic rays which encounter the Earth's atmosphere produce showers of muons and high-energy photons, which can be detected using a smartphone camera. The CRAYFIS experiment was devised to observe cosmic rays at ultra-high energy (UHE) using the existing network of smartphones as a ground detector array. We'll describe our custom app, our lab measurements of smartphone efficiency, and our latest projections for the sensitivity of the CRAYFIS array to UHE cosmic rays.
Friday, March 27, 2015
3:30 PM
Physics Building, Room 204
Note special room.
"A new way to image: MRI with a 10,000,000-fold increase in sensitivity"
Gordon Cates , University of Virginia
[Host: Dinko Pocanic]
Friday, March 20, 2015
3:30 PM
Physics Building, Room 204
Note special room.
"Screening of charge and structural motifs in oxides"
Peter Littlewood , Argonne National Laboratory and University of Chicago
[Host: Despina Louca]
The boundary between metal and insulator remains a fruitful source of emergent phenomena in materials, ranging from oxides, to cold atoms. Typically the insulating side of this boundary is occupied by an electronic crystal (though often disordered), and at higher temperatures a polaronic liquid or bad metal. While the paradigm Hamiltonian for this transition involves only short –range electronic correlations, in practice the transition is tuned by disorder, by screening of longer range Coulomb forces, and by coupling to the lattice. These lectures will discuss a few of these phenomena in real oxide systems including bulk and interface transition metal oxides.
Heterostructure oxides offer the opportunity to build in electric fields by precise control of chemistry on the atomic scale, used recently to generate modulation doping of two- dimensional electron gases (2DEG) in oxides. The origin of the 2DEG, whether in pristine or defected materials, is under debate. I will discuss the role of surface redox reactions, in particular O vacancies, as the source of mobile carriers, and also discuss their role in the switching of ferroelectricity in ultra-thin films.
While electric charges can be screened by mobile carriers, the same is not true of strain fields, which have intrinsic long-range interactions that cannot be screened. When strain fields are produced as a secondary order parameter in phase transitions - as for example in ferroelectrics - this produces unexpected consequences for the dynamics of order parameter fluctuations, including the generation of a gap in what would otherwise have been expected to be Goldstone modes. In some cases, eg manganites and nickelates, other intra-cell modes can nonlinearly screen the order parameter, which produces a strong sensitivity of ordering to octahedral rotations, essentially a jamming transition. This is relevant for tuning entropic effects at phase transitions, perhaps to enhance electro-caloric effects.
Friday, February 27, 2015
3:30 PM
Physics Building, Room 204
Note special room.
"Quantum-gas physics in orbit: prospects for microgravity Bose-Einstein condensates aboard NASA's Cold Atom Laboratory"
Nathan Lundblad , Bates College
[Host: Cass Sackett]
Notions of geometry, topology, and dimensionality have directed the historical development of quantum-gas physics, as has a relentless search for longer-lived matter-wave coherence and lower absolute temperature. With a toolbox of forces for confinement, guiding, and excitation, physicists have used quantum gases to test fundamental ideas in quantum theory, statistical mechanics, and in recent years notions of strongly-correlated many-body physics from the condensed-matter world. Some of this work has been hampered by terrestrial gravity; levitation schemes of varying degree of sophistication are available, as are atomic-fountain and drop-tower microgravity facilities, but the long-term free-fall environment of low-Earth orbit remains a tantalizing location for quantum-gas experiments.
I will review a planned NASA microgravity program set to launch to the International Space Station in 2016. One set of experiments will explore a trapping geometry for quantum gases that is both theoretically compelling and difficult to attain terrestrially: that of a spherical or ellipsoidal shell. This trap could confine a Bose-Einstein condensate to the surface of an experimentally-controlled “bubble.” Other experiments will focus on atom interferometry and few-body physics. I will also review recent terrestrial work tailoring periodic geometries for BEC toward interesting solid-state analogues.
Wednesday, February 25, 2015
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
"From correlated topological insulators to iridates and spin liquids"
Stephan Rachel , Dresden University of Technology
[Host: Joe Poon]
The non-interacting topological insulators (TIs) have attracted great interest in the last decade. While this class of materials is today well-understood, the effect of electron-eletron interactions in such systems remains in general elusive. In this talk, I will address two different aspects of interactions in 2D topological band structures: (i) in some cases, strongly interacting TI models can be used to describe the exotic magnetic properties of certain transition metal oxides. (ii) in other cases, strong interactions can drive a TI into spin-liquid phases.
Friday, February 20, 2015
3:30 PM
Physics Building, Room 204
Note special room.
"Inflation, Dark Matter, and Gravity Waves"
Qaisar Shafi , Bartol Institute, University of Delaware
[Host: PQ Hung]
The Standard Model of strong and electroweak interactions, together with Einstein's theory of general relativity, provide the basis for the highly successful hot big bang cosmology. A large quantity of groundbreaking cosmological observations favor an epoch of primordial inflation, during which the very early universe experienced an exponentially rapid expansion phase before transitioning to a hot, radiation dominated ('big bang') phase. The present universe, it is now widely accepted, is largely dominated by dark energy, whose nature is entirely mysterious, and also by dark matter, presumably consisting of some relic and still undetected elementary particle.
Some aspects of inflationary cosmology will be reviewed, including its prediction concerning the existence of primordial gravity waves whose discovery would have profound implications for high energy physics and cosmology.
Thursday, February 19, 2015
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
"Uncovering the Fibonacci Phase in Z3 Parafermion Systems"
Miles Stoudenmire , Perimeter Institute
[Host: Joe Poon]
Recently there has been great progress in realizing platforms for topological quantum computation, with mounting evidence of the experimental observation of Majorana zero modes. However, braiding such zero modes does not yield a set of transformations sufficient to perform universal, fault tolerant computation. One way forward is to engineer systems realizing Z3 parafermion zero modes, which generalize Majorana zero modes. Coupled Z3 parafermions could hybridize into a phase supporting bulk Fibonacci anyons, a type of non-Abelian anyon that does have universal braiding statistics.
Using the density matrix renormalization group (DMRG), we study a two-dimensional model of coupled Z3 parafermions. By working close to the weakly-coupled chain limit, we are able to identify the Fibonacci phase on cylinders as small as four sites in circumference then track its evolution, finding it survives even to the isotropic limit of our model on larger cylinders. We examine the extent of this phase and the wider phase diagram of our model, which turns out to harbor a second topological phase.
Friday, February 13, 2015
3:30 PM
Physics Building, Room 204
Note special room.
"First-principles studies of oxide surfaces and interfaces"
Andrei Malashevich , Yale University
[Host: Joe Poon]
Quantum-mechanical calculations based on methods that do not require any empirical input (first-principles calculations) have become an indispensable tool in studies of materials properties. In this talk, I will focus on applications of first-principles methods to studies of perovskite oxide surfaces and interfaces. Depending on the choice of cations, oxides can have almost any desired property. I will present two examples of materials that exhibit relation between structure and electronic properties at surfaces and interfaces. First, I will discuss an interface between metallic LaNiO3 thin film and ferroelectric PbTiO3. The polar field created by a ferroelectric can be used to modulate the conductivity of a channel material. This allows one to design non-volatile electronic devices based on the ferroelectric field effect. Typically, in the ferroelectric field effect, switching the polar state of a ferroelectric changes the carrier density in the channel material. I will show that in the LaNiO3/PbTiO3 interface the conductivity of the interface changes due to changes in carrier mobility, which in turn is related to structural distortions at the interface and appearance of two-dimensional conductivity in PbTiO3 at the interface. Second, I will present a study of properties of the (001) surfaces of thin LaNiO3 films. These films show dramatic differences in conductivity depending on the surface termination (LaO vs NiO2). We find that in this case, the conductivity is related to the polar structural distortions appearing at the surfaces of films.
Monday, February 9, 2015
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
"Phase incoherence driven melting of order parameters in cuprate high temperature superconductors and disordered charge density wave systems"
Utpal Chatterjee , University of Virginia
[Host: Joe Poon]
Charge density waves (CDWs) and superconductivity are canonical examples of symmetry breaking in materials. Both are characterized by a complex order parameter – namely an amplitude and a phase. In the limit of weak coupling and in the absence of disorder, the formation of pairs (electron-electron for superconductivity, electron-hole for CDWs) and the establishment of macroscopic phase coherence both occur at the transition temperature Tc that marks the onset of long-range order. But, the situation may be different at strong coupling or in the presence of disorder. We have performed extensive experimental investigations on pristine and intercalated samples of 2H-NbSe2, a CDW material with strong electron-phonon coupling, using a combination of structural (X-ray), spectroscopic (photoemission and tunnelling) and transport probes. We find that Tc(δ) is suppressed as a function of the concentration (δ) of the intercalated atoms and eventually vanishes at a critical value of δ=δc leading to quantum phase transition (QPT). Our integrated approach provides clear signatures that the phase of the order parameter becomes incoherent at the quantum/ thermal phase transition, although the amplitude remains finite over an extensive region above Tc and beyond δc. This leads to the persistence of an energy gap in the electronic spectra even though there is no long-range order, a phenomenon strikingly similar to the so-called pseudogap in completely different systems such as high temperature superconductors, disordered superconducting thin films and cold atoms.
Friday, February 6, 2015
3:30 PM
Physics Building, Room 204
Note special room.
"Stiffness from disorder in frustrated quasi-two-dimensional magnets"
Gia-Wei Chern , Los Alamos National Lab
[Host: Joe Poon]
Frustrated magnetism has become an extremely active field of research. The concept of geometrical frustration dates back to Wannier’s 1950 study of Ising antiferromagnet on the triangular lattice. This simple system illustrates many defining characteristics of a highly frustrated magnet, including a macroscopic ground-state degeneracy and the appearance of power-law correlations without criticality. In this talk I will discuss a simple generalization of the triangular Ising model, namely, a finite number of vertically stacked triangular layers. Our extensive numerical simulations reveal a low temperature reentrance of two Berezinskii-Kosterlitz-Thouless transitions. In particular, I will discuss how short-distance spin-spin correlations can be enhanced by thermal fluctuations, a phenomenon we termed stiffness from disorder. This is a generalization of the well-known order-by-disorder mechanism in frustrated magnets. I will also present an effective field theory that quantitatively describes the low-temperature physics of the multilayer triangular Ising antiferromagnet.
Friday, January 16, 2015
3:30 PM
Physics Building, Room 204
Note special room.
"Jamming and the Anticrystal"
Andrea Liu , University of Pennsylvania
[Host: Seunghun Lee & Israel Klich]
When we first learn the physics of solids, we are taught the theory of perfect crystals. Only later do we learn that in the real world, all solids are imperfect. The perfect crystal is invaluable because we can describe real solids by perturbing around this extreme limit by adding defects. But such an approach fails to describe a glass, another ubiquitous form of rigid matter. I will argue that the jammed solid is an extreme limit that is the anticrystal--an opposite pole to perfect order. Like the perfect crystal, it is an abstraction that can be understood in depth and used as a starting point for understanding the mechanical properties of solids with surprisingly high amounts of order. Unlike the crystal, it is also a starting point for developing mechanical metamaterials whose Poisson ratios can be tuned anywhere from the completely incompressible to the completely auxetic limit.
Friday, December 5, 2014
3:30 PM
Physics Building, Room 204
Note special room.
"Massless and Massive Electrons: Relativistic Physics in Condensed Matter Systems"
Vidya Madhavan , University of Illinois at Urbana-Champaign
[Host: Jeffrey Teo]
Electrons in free space have a well-defined mass. Recently, a new class of materials called topological insulators were discovered, where the low energy electrons have zero mass. In fact, these electrons can be described by the same massless Dirac equation that is used to describe relativistic particles travelling close to the speed of light. In this talk I will describe our recent experimental and theoretical investigations of a class of materials called Topological Crystalline Insulators (TCIs) [1]. TCIs are recently discovered materials [2,3] where topology and crystal symmetry intertwine to create linearly dispersing Fermions similar to graphene. To study this material we used a scanning tunneling microscope [3,4,5]. With the help of our high-resolution data, I will show how zero-mass electrons and massive electrons can coexist in the same material. I will discuss the conditions to obtain these zero mass electrons as well the method to impart a controllable mass to the particles and show how our studies create a path to engineering the Dirac band gap and realizing interaction-driven topological quantum phenomena in TCIs.
[1] L. Fu, Topological Crystalline Insulators. Phys. Rev. Lett. 106, 106802 (2011).
[2] T. H. Hsieh et al., Topological crystalline insulators in the SnTe material class. Nat.Commun. 3, 982 (2012).
[3] Y. Okada, et al., Observation of Dirac node formation and mass acquisition in a topological crystalline insulator, Science 341, 1496-1499 (2013)
[4] Ilija Zeljkovic, et al., Mapping the unconventional orbital texture in topological crystalline insulators, Nature Physics 10, 572–577 (2014)
[5] Ilija Zeljkovic, et al., Dirac mass generation from crystal symmetry breaking on the surfaces of topological crystalline insulators, arXiv:1403.4906
Friday, November 21, 2014
3:30 PM
Physics Building, Room 204
Note special room.
"Twists in quantum magnets"
David Alan Tennant , Spallation Neutron Source, Oak Ridge National Laboratory
[Host: Seunghun Lee]
Neutrons provide the ability to look at quantum states of matter in unrivaled detail. Using quantum magnets in conjunction with magnetic fields exotic phases of matter can be generated that are highly quantum entangled. The wave functions in these states can be probed in space and time and in quantum critical states in particular elaborate symmetries and strange properties like fractional quantum numbers are revealed. In this talk I will show some of the remarkable physics that can be explored and how neutron scattering can be used to investigate what is going on.
Friday, November 14, 2014
3:30 PM
Physics Building, Room 204
Note special room.
"Screening of charge and structural motifs in oxides"
CANCELED Peter Littlewood , Argonne National Laboratory
[Host: Despina Louca]
The boundary between metal and insulator remains a fruitful source of emergent phenomena in materials, ranging from oxides, to cold atoms. Typically the insulating side of this boundary is occupied by an electronic crystal (though often disordered), and at higher temperatures a polaronic liquid or bad metal. While the paradigm Hamiltonian for this transition involves only short –range electronic correlations, in practice the transition is tuned by disorder, by screening of longer range Coulomb forces, and by coupling to the lattice. These lectures will discuss a few of these phenomena in real oxide systems including bulk and interface transition metal oxides.
Heterostructure oxides offer the opportunity to build in electric fields by precise control of chemistry on the atomic scale, used recently to generate modulation doping of two- dimensional electron gases (2DEG) in oxides. The origin of the 2DEG, whether in pristine or defected materials, is under debate. I will discuss the role of surface redox reactions, in particular O vacancies, as the source of mobile carriers, and also discuss their role in the switching of ferroelectricity in ultra-thin films.
While electric charges can be screened by mobile carriers, the same is not true of strain fields, which have intrinsic long-range interactions that cannot be screened. When strain fields are produced as a secondary order parameter in phase transitions - as for example in ferroelectrics - this produces unexpected consequences for the dynamics of order parameter fluctuations, including the generation of a gap in what would otherwise have been expected to be Goldstone modes. In some cases, eg manganites and nickelates, other intra-cell modes can nonlinearly screen the order parameter, which produces a strong sensitivity of ordering to octahedral rotations, essentially a jamming transition. This is relevant for tuning entropic effects at phase transitions, perhaps to enhance electro-caloric effects.
Friday, November 7, 2014
3:30 PM
Physics Building, Room 204
Note special room.
There are three open questions in physics which seem unrelated: Why is there only matter around us? How neutrinos acquire their tiny masses? Why all the particles in Nature have integer electric charge? It turns out that these open questions may be related. In this talk I will explain the questions, the connection between them and describe the on-going theoretical and experimental efforts in understanding them.
Friday, October 31, 2014
3:30 PM
Physics Building, Room 204
Note special room.
"Hoping to get something out of nothing: Vacuum fluctuations and Newtonian (?) gravity"
Ricardo Decca , IUPUI
[Host: Genya Kolomeisky & Israel Klich]
This talk deals with measurements of small forces at sub-micron separations. It tries to address an innocent enough question: Is Newtonian gravity valid at all distances? I will try to convey the deep sense of ignorance we still have in this topic, and describe the efforts undertaken to advance our knowledge. In particular, our experiments are sensitive to Yukawa-like corrections (i.e. interactions mediated by massive bosons) in the 0.1 to 1 micron range.
It will be shown that when trying to measure the gravitational interaction at short separations (on the order of 100 nm), other forces have to be taken into account. Among them, vacuum fluctuations are the more ubiquitous ones.
A brief description of how macroscopic bodies (classical objects) interact with vacuum fluctuations (a purely quantum effect) will be presented… towards developing approaches that are insensitive to them! These approaches use an engineered sample which allows to establish better constraints in Yukawa-like interactions. This is accomplished by measuring the difference in forces in configurations where vacuum fluctuations are the same, but the corrections to Newtonian gravity (if any) are not.
Friday, October 17, 2014
3:30 PM
Physics Building, Room 204
Note special room.
"Fermion space charge in narrow-band gap semiconductors, Weyl semimetals and around highly charged nuclei"
Genya Kolomeisky , University of Virginia
[Host: Dinko Pocanic]
The field of charged impurities in narrow-band gap semiconductors and Weyl semimetals can create electron-hole pairs when the total charge $Ze$ of the impurity exceeds a value $Z_{c}e.$ The particles of one charge escape to infinity, leaving a screening space charge. The result is that the observable dimensionless impurity charge $Q_{\infty}$ is less than $Z$ but greater than $Z_{c}$. There is a corresponding effect for nuclei with $Z >Z_{c} \approx 170$, however in the condensed matter setting we find $Z_{c} \simeq 10$. Thomas-Fermi theory indicates that $Q_{\infty} = 0$ for the Weyl semimetal, but we argue that this is a defect of the theory. For the case of a highly-charged recombination center in a narrow band-gap semiconductor (or of a supercharged nucleus), the observable charge takes on a nearly universal value. In Weyl semimetals the observable charge takes on the universal value $Q_{\infty} = Z_{c}$ set by the reciprocal of material's fine structure constant.
Friday, October 10, 2014
3:30 PM
Physics Building, Room 204
Note special room.
"The Sacred Volcano, and other true stories from North Korea"
Richard Stone , American Association for the Advancement of Science
[Host: Seunghun Lee]
Friday, October 3, 2014
3:30 PM
Physics Building, Room 204
Note special room.
With the observation of the Higgs Boson in July 2012, high energy physics has claimed victory in accounting for all the known particles within the Standard Model of Particle Physics. However, great and profound questions remain unanswered regarding the nature of energy, matter, space and time. Among these questions is "What is the nature of Dark Matter" that accounts for approximately 80% of the matter in the universe. Gaining popularity is to invoke the possibility that "Non-WIMPy" new particles form the dark matter in contrast to usual Weakly Interacting Massive Particles hypothesis. Novel ideas and novel experiments, often at a very small scale, are exploring large areas of previously unexplored parameter space. Plus, they are a lot of fun too!
Friday, September 26, 2014
3:30 PM
Physics Building, Room 204
Note special room.
"AS I REMEMBER. A Walk Through My Years at Hughes Aircraft"
Scott Walker , Hughes Aircraft and GM Hughes Electronics
[Host: Joe Poon]
The basic theme of the talk is to emphasize the value of a physics degree when dealing with a wide spectrum of technical products and systems. Following the story line of his career as presented in his recent autobiography “As I Remember”, Scott will discuss the development of a number of military systems, US and international. In a light handed manner, he will summarize some community projects such as the Discovery Science Center in southern California, funding of a tax initiative for improved local transportation, and the formation by local businesses of the Robert Saunders scholarship for the school of engineering at UC Irvine. He will relate his physics background to the development of new semiconductor components and advanced automotive electronics, including the development of the EV-1, the first US commercial all electric vehicle by GM.
Bio: Dr. Walker received his Ph.D. in nuclear physics from the University of Virginia in 1961. Moving to California upon graduation, he joined Hughes Aircraft Company later to become GM Hughes Electronics. Over the next 37 years at Hughes he was given increasingly wide management responsibilities for the design and production of military systems, advanced industrial electronic components, international programs for air traffic control systems, both military and commercial, and advanced automotive electronics. Retiring in 1997 as Corporate Senior Vice President and member of the Office of the Chairman, Scott and his wife of fifty six years now reside in Indianapolis, Indiana.
Friday, September 19, 2014
3:30 PM
Physics Building, Room 203
Note special room.
"Hoo's going to help me? START to help you keep the evidence"
Ralph Allen , University of Virginia, Environmental Health & Safety
[Host: Rick Marshall]
Accidents in academic research labs around the country have called attention to the lack of attention to safety when researchers assume that students understand the risks in their labs. Many of the hazardous materials have become increasingly regulated and granting agencies are now demanding evidence that environmental and safety regulations are followed. The first thing that regulators review are training records. The Office of Environmental Health and Safety has developed a program to help researchers document training and assist in improving laboratory safety.
Friday, September 12, 2014
3:30 PM
Physics Building, Room 204
Note special room.
"Quantum microscopy with NV centers in diamonds"
Alex Retzker , The Hebrew University of Jerusalem
[Host: Israel Klich]
In recent years there has been a growing effort to develop a new type of microscopy, which is based on the NV (Nitrogen Vacancy) centers in diamonds. In this colloquium I will overview the latest results in this field and present a few quantum enhanced measurement schemes to image single protons using NV centers in diamond. These schemes will use ideas from quantum coherent control and quantum computing and will mainly target imaging with biological goals.
Friday, August 29, 2014
3:30 PM
Physics Building, Room 204
Note special room.
"The Life and Death of a Drop: Transitions and Singularities"
Sidney Nagel , University of Chicago
[Host: Seunghun Lee]
The exhilarating spray from waves crashing onto the shore, the distressing sound of a faucet leaking in the night, and the indispensable role of bubbles dissolving gas into the oceans are but a few examples of the ubiquitous presence and profound importance of drop formation and splashing in our lives. They are also examples of a liquid changing its topology as it breaks into pieces. Although part of our common everyday experience, these changes are far from understood and reveal profound surprises upon careful investigation. For example, in droplet fission the fluid forms a neck that becomes vanishingly thin at the point of breakup so that there is a dynamic singularity in which physical properties such as pressure diverge. Singularities of this sort often organize the overall dynamical evolution of nonlinear systems. In this lecture, I will give the life history of a drop – from its birth to its eventual demise – illustrating the passage of its existence with the scientific surprises that determine its fate.
Friday, April 25, 2014
3:30 PM
Physics Building, Room 204
Note special room.
Friday, April 18, 2014
3:30 PM
Physics Building, Room 203
Note special room.
"String Theory, Our Real World, and Higgs bosons"
Gordon Kane , University of Michigan
[Host: Dinko Pocanic]
Friday, April 11, 2014
3:30 PM
Physics Building, Room 204
Note special room.
"Unveiling the order of the high temperature superconductors"
Subir Sachdev , Harvard University
[Host: Seunghun Lee]
Friday, April 4, 2014
3:30 PM
Physics Building, Room 204
Note special room.
This talk will discuss the opportunities for the exploration of physical systems that have not heretofore existed in the natural world.
Friday, February 21, 2014
3:30 PM
Physics Building, Room 204
Note special room.
"Quantum computing with hypercubes of light"
Pei Wang , University of Virginia
[Host: Olivier Pfister]
In this colloquium, I will first explain continuous variable one-way quantum computing, cluster states, and then present our new proposal of a simple, "top-down" setup to generate large-size, D-hypercubic-lattice CV cluster states of more than 6000 entangled modes using D identical optical parametric oscillators (OPOs), each with a two-frequency pump [6]. These cluster states are sufficient for universal one-way quantum computation [3], and the high dimensional lattices are useful in quantum error correction based on Kitaev's surface code [7]. Our optical construction methods eschews the limitations of a three-dimensional world, enabling simulation of measurements on these high-valence cluster graphs and also inviting theoretical and experimental investigations of their topological properties [8].
References:
1. P.W.Shor, in Proceedings, 35th Annual Symposium on Foundations of Computer Science, edited by S.Goldwasser(IEEE press, Los Alamitos, CA, Santa Fe, NM,1994) pp. 124-134.
2. R.P.Feynman, Int.J.Theor.Phys.21,467 (1982)
3. R.Raussendorf and H.J.Briegel, "A one-way quantum computer", Phys.Rev.Lett. 86,5188(2001)
4. M.Pysher et al., "Parallel generation of quadripartite cluster entanglement in the optical frequency comb", Phys.Rev.Lett. 107, 030505(2011)
5. M.Chen, N.C.Menicucci,and O.Pfister,"Experimental realization of multipartite entanglement of 60 modes of the quantum optical frequency comb", arXiv:1311.2957[quant-ph](2013)
6. P.Wang, M.Chen, N.C.Menicucci,and O.Pfister,"Weaving quantum optical frequency combs into hypercubic cluster states", arXiv:1309.4105[quant-ph] (2013)
7. R.Raussendorf, J.Harrington, and K.Goyal,"A fault-tolerant one-way quantum computer", Ann. Phys.(N.Y.) 321, 2242–2270 (2006)
8. T. F. Demarie, T. Linjordet, N. C. Menicucci, and G. K. Brennen, Detecting Topological Entanglement Entropy in a Lattice of Quantum Harmonic Oscillators, arXiv:1305.0409 [quant-ph] (2013)
Friday, February 14, 2014
3:30 PM
Physics Building, Room 203
Note special room.
"String Theory, Our Real World, and Higgs bosons"
Gordon Kane , University of Michigan
[Host: Dinko Pocanic]
Friday, January 31, 2014
3:30 PM
Physics Building, Room 204
Note special room.
"Universality in the Magnetic Response of Metamagnetic Materials"
Pradeep Kumar , University of Florida
[Host: Bellave Shivaram]
Friday, December 6, 2013
3:30 PM
Physics Building, Room 204
Note special room.
"Non-equilibrium statistical physics, population genetics and evolution"
Marija Vucelja , Rockefeller University
[Host: Joe Poon]
Friday, November 22, 2013
3:30 PM
Physics Building, Room 204
Note special room.
"Neutrinos: Masters of Surprise"
Bob McKeown , Jefferson Lab
[Host: Nilanga Liyanage & Gordon Cates]
Friday, November 15, 2013
3:30 PM
Physics Building, Room 204
Note special room.
"Recent Discoveries of Cosmic Ray Anomalies"
Eun-Suk Seo , University of Maryland
[Host: Craig Group]
Friday, October 25, 2013
3:30 PM
Physics Building, Room 204
Note special room.
Friday, October 4, 2013
3:30 PM
Physics Building, Room 204
Note special room.
"Particle and Nuclear physics with cold neutrons"
Nadia Fomin , University of Tennessee, Knoxville
[Host: Dinko Pocanic]
Friday, September 27, 2013
3:30 PM
Physics Building, Room 204
Note special room.
"Experiences with a "Jackson by Inquiry" electromagnetism course and the connection with neural networks, recent cognitive neuroscience, and modern theories of teaching/learning"
Bruce Patton , The Ohio State University
[Host: Joe Poon]
Friday, September 20, 2013
3:30 PM
Physics Building, Room 204
Note special room.
"The Interplay Between the Top Quark and the Higgs Boson: How a discovery from a generation ago can help us understand the latest breakthrough in particle physics"
Chris Neu , University of Virginia
[Host: Joe Poon]
Friday, August 30, 2013
3:30 PM
Physics Building, Room 204
Note special room.
"When a theorist met an experimentalist or vice versa"
Israel Klich & Seunghun Lee , University of Virginia
[Host: Joe Poon]
Friday, April 26, 2013
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Bloch, Landau, and Dirac: Hofstadter's Butterfly in Graphene"
Philip Kim , Columbia University
[Host: Seunghun Lee]
New developments in particle physics offer a new and radically simple conception of the universe. Fundamental particles called quarks and leptons make up everyday matter, and two new laws of nature rule their interactions. Until July 4, 2012, our neat story was missing one piece, a particle called the Higgs boson. Without it, there would be no atoms, no chemistry, no liquids or solids, and no basis for life. Why did thousands of physicists devote decades to the hunt, and how does the “discovery of the century” change the way we see the world?
Friday, April 12, 2013
4:00 PM
Physics Building, Room 203
Note special time.
Note special room.
"Nonlinear optics at the nanoscale Physics"
Eric Mazur , Harvard University
[Host: Kevin Lehmann & Brad Cox]
Friday, April 5, 2013
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Current Results in Neutrino Physics"
Christopher White , Illinois Institute of Technology
[Host: Craig Dukes]
Friday, March 29, 2013
4:00 PM
Physics Building, Room 204
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Note special room.
Friday, March 1, 2013
4:00 PM
Physics Building, Room 204
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Note special room.
"Emergent phenomena and universality in quantum systems far from thermal equilibrium"
Ehud Altman , Weizmann Institute
[Host: Israel Klich]
Friday, February 22, 2013
4:00 PM
Physics Building, Room 203
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Note special room.
Friday, February 1, 2013
4:00 PM
Physics Building, Room 204
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Note special room.
"Superconducting Quarks: Condensed Matter in the Heavens"
Mark Alford , Washington University in St. Louis
[Host: Diana Vaman]
Friday, January 18, 2013
4:00 PM
Physics Building, Room 204
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Note special room.
"Exploring topological states with cold atoms and photons"
Eugene Demler , Harvard University
[Host: Israel Klich]
Friday, December 7, 2012
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Clusters, Correlations, and Quarks: A High-Energy Perspective on Nuclei"
John Arrington , Argonne National Laboratory
[Host: Donal Day]
Friday, November 30, 2012
4:00 PM
Physics Building, Room 204
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Note special room.
"The Supernova Early Warning System (SNEWS)"
Alec Habig , University of Minnesota Duluth
[Host: Craig Dukes]
Friday, November 16, 2012
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Topological Band Theory and Twisted Multilayer Graphene"
Gene Mele , University of Pennsylvania
[Host: Genya Kolomeisky]
Friday, November 9, 2012
4:00 PM
Physics Building, Room 204
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Note special room.
"Bright Coherent Ultrafast X-Ray Beams on a Tabletop and Applications in Nano and Materials Science"
Margaret Murnane , University of Colorado at Boulder
[Host: Reihaneh Shahrokhshahi]
1. Popmintchev et al, Science 336, 1287 (2012).
2. Mathias, et al, PNAS 109, 4792 (2012).
3. Rudolf et al., Nature Commun 3, 1037 (2012).
Friday, October 12, 2012
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Friday, October 5, 2012
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Friday, September 28, 2012
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Friday, September 21, 2012
4:00 PM
Physics Building, Room 204
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Note special room.
"Quantum fluctuations: From the Casimir Effect to Quantum Entanglement"
Israel Klich , University of Virginia
[Host: Joe Poon]
Friday, September 14, 2012
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Higgs Boson Searches at the CDF Experiment: Highlights of UVa Contributions to a Successful Search with the Full Data Set"
Craig Group , University of Virginia
[Host: Joe Poon]
Friday, September 7, 2012
4:00 PM
Physics Building, Room 204
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Note special room.
"Devoting your life to scientific research does not mean that you should actually risk your life and granting as well as regulatory agencies will make sure that you don't"
Ralph Allen , University of Virginia
[Host: Rick Marshall]
Friday, August 31, 2012
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Graphene: how electrons move and interact in the ultimate flatland"
Enrico Rossi , College of William & Mary
[Host: Genya Kolomeisky]
Friday, April 27, 2012
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"101 Years of Superconductivity - My Contributions Therein"
Bellave Shivaram , University of Virginia
[Host: Brad Cox]
Thursday, April 12, 2012
7:00 PM
Chemistry Building, Room 402
Note special date.
Note special time.
Note special room.
"The National Ignition Facility: Pathway to Energy Security and Physics of the Cosmos"
Edward Moses , National Ignition Facility
[Host: Brad Cox]
The National Ignition Facility (NIF), at Lawrence Livermore National Laboratory in Livermore, California, is the world’s most energetic laser system. NIF is capable of producing over 1.8 MJ and 500 TW of ultraviolet light, 100 times more than any other operating laser. Completed in March 2009, it is maturing rapidly and transitioning into the world’s premier high-energy-density science experimental facility, while supporting its strategic security, fundamental science, and energy security missions.
By concentrating intense laser energy into target only millimeters in length, NIF can, for the first time, produce conditions emulating those found in planetary interiors and stellar environments and creating fusion energy to power our future. The extreme conditions of energy density, pressure, and temperature will enable scientists to pursue fundamental science experiments designed to address a range of scientific questions, from observing new states of matter to exploring the origin of ultrahigh-energy cosmic rays. Early experiments have been successfully completed in support of materials equations of state, materials strength, and radiation transport in extreme temperature and pressure conditions.
The National Ignition Campaign, an international effort pursued on the NIF, aims to demonstrate fusion burn and generate more energy output than the laser energy delivered to the target. Achieving this ignition goal will validate the viability of inertial fusion energy (IFE) as a clean source of energy. A laser-based IFE power plant will require advances in high-repetition-rate lasers, large-scale target fabrication, target injection and tracking, and other supporting technologies. These capabilities could lead to an operational prototype IFE power plant in 10 to 15 years. LLNL, in partnership with academia, national laboratories, and industry, is developing a Laser Inertial Fusion Energy (LIFE) baseline design concept and examining technology choices for developing a LIFE prototype power plant.
This talk will describe the unprecedented experimental capabilities of the NIF, its role in strategic security and fundamental science, and the pathway to achieving fusion ignition to create a clean and secure energy future.
Friday, April 6, 2012
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Fundamental measurements of the proton's sub-structure using high-energy polarized proton-proton collisions "
Bernd Surrow , Temple University
[Host: Nilanga Liyanage]
Friday, March 23, 2012
4:00 PM
Physics Building, Room 203
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Note special room.
"A Scientific Analysis of 21st Century Environmental and Economic Challenges"
Sir David King , Smith School at Oxford
[Host: John T. Yates, Jr., Ian Harrison, & Brad Cox]
Well designed technological solutions are desirable and can be compatible with the continued growth of human wellbeing. The socio-political challenges in directing such a collective response are beyond anything previously managed. This may well lead to a mid-century slide into conflict caused by environmental and resource-driven challenges on a scale not previously experienced. The thesis presented here is that meeting these challenges will require a global cultural and technological transformation on much the same scale as the European Renaissance or the Industrial Revolution itself, and a clear understanding by all societies of the need to adapt and strengthen global governance procedures. Decision making at all levels will require significantly enhanced knowledge and understanding.
Thursday, March 15, 2012
3:30 PM
Physics Building, Room 203
Note special date.
Note special room.
"Tales from the Darkside of Particle Physics"
Bill Marciano , Brookhaven National Laboratory
[Host: INPP]
Friday, March 2, 2012
4:00 PM
Physics Building, Room 204
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Note special room.
"The Next Generation of Nuclear Reactor Designs"
Sama Bilbao Y Leon , Virginia Commonwealth University
[Host: Simonetta Liuti]
Thursday, February 23, 2012
3:30 PM
Physics Building, Room 204
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Note special room.
"Imaging the microscopic structure of shear thinning and thickening colloidal suspensions"
Xiang Cheng , Cornell University
[Host: Seunghun Lee]
Monday, February 20, 2012
3:30 PM
Physics Building, Room 204
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Note special room.
"Spin Ice and Quantum Spin Liquid in Geometrically Frustrated Magnets"
Haidong Zhou , National High Magnetic Field Lab
[Host: Seunghun Lee]
Thursday, February 16, 2012
3:30 PM
Physics Building, Room 204
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Note special room.
Monday, February 13, 2012
3:30 PM
Physics Building, Room 204
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Note special room.
"Pseudo-spin Resolved Transport Spectroscopy of the Kondo Effect"
Sami Amasha , Stanford University
[Host: Seunghun Lee]
Friday, February 10, 2012
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"The Lead Radius Experiment PREX"
Robert W. Michaels , Thomas Jefferson National Accelerator Facility
[Host: Xiaochao Zheng]
Thursday, February 9, 2012
3:30 PM
Physics Building, Room 204
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Note special room.
"Tailoring Dirac Fermions in Molecular Graphene"
Kenjiro Gomes , Stanford University
[Host: Seunghun Lee]
Friday, January 27, 2012
4:00 PM
Physics Building, Room 204
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Note special room.
For the case of two or more electrons, the interaction of the electrons with the phonon field gives rise to an effective attraction between electrons that causes the particles to bind together. For N electrons, N → ∞, the systems are unstable in the sense that the binding energy grows faster than linearly in N. We will discuss recent work with Frank, Lieb, and Seiringer which shows that sufficiently strong Coulomb repulsion between electrons can compensate for this binding and provide stability for polaron systems for large N.
Thursday, January 26, 2012
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
"Characterizing phase diagram of High Temperature Superconductors via Angle Resolved Photoemission Spectroscopy"
Utpal Chatterjee , Argonne National Laboratory
[Host: Seunghun Lee]
Friday, January 20, 2012
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Putting the Genie Back in the Bottle: The Science of Nuclear Non-Proliferation"
Jerry Gilfoyle , University of Richmond
[Host: Simonetta Liuti]
Friday, December 2, 2011
4:00 PM
Physics Building, Room 204
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Note special room.
"How Green Can Algae Be? Alternative Energy from the Chesapeake Algae Project"
William Cooke , College of William and Mary
[Host: Tom Gallagher]
Friday, November 18, 2011
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Searching for Supersymmetry at the LHC"
Daniel Elvira , Fermi National Accelerator Lab
[Host: Brad Cox]
Monday, November 14, 2011
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
"Peering into dark corners at Fermilab and CERN"
Bob Hirosky , University of Virginia
[Host: Joe Poon]
Friday, November 11, 2011
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Atomic calculations for tests of fundamental physics"
Marianna Safronova , University of Delaware
[Host: Kent Paschke]
Friday, November 4, 2011
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Nearly perfect fluidity: From cold atoms to hot quarks and gluons"
Thomas Schaefer , North Carolina State University
[Host: Peter Arnold]
Thursday, November 3, 2011
3:30 PM
Physics Building, Room 204
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Note special room.
Monday, October 31, 2011
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
"What Have We Learned from Electron Deep Inelastic Scattering?"
Xiaochao Zheng , University of Virginia
[Host: Joe Poon]
Friday, October 28, 2011
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Topological Insulators: From Fundamentals to Applications"
Di Xiao , Oak Ridge National Lab
[Host: Joe Poon]
Thursday, October 27, 2011
4:00 PM
Physics Building, Room 204
Note special date.
Note special time.
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"Diving For Treasure In Complex Data "
Marvin Weinstein , Stanford University
[Host: Simonetta Liuti]
Wednesday, October 26, 2011
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
"Statistical mechanics and dynamics of multicomponent quantum gases"
Austen Lamacraft , University of Virginia
[Host: Joe Poon]
Friday, October 14, 2011
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Friday, October 7, 2011
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Multi-Photon and Entangled-Photon Imaging and Lithography"
Malvin Teich , Boston University
[Host: Lauren Levac]
Friday, September 30, 2011
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"The cultural and ethical world of nuclear weapons scientists"
Hugh Gusterson , George Mason University
[Host: Seunghun Lee]
Friday, September 16, 2011
4:00 PM
Physics Building, Room 204
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Note special room.
"Electronic Detection and Diagnosis of Health and Illness of Premature Infants"
John Delos , College of William and Mary
[Host: Tom Gallagher]
Friday, September 2, 2011
4:00 PM
Physics Building, Room 204
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Note special room.
"Having your cake and seeing it too: In Situ Observation of Incompressible Mott Domains in Ultracold Atomic Gases"
Cheng Chin , University of Chicago
[Host: Seunghun Lee]
Friday, April 29, 2011
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Application of Machine Learning Methods to Genome-Wide Maps of Histone Methylations"
Stefan Bekiranov , UVA Medical School
[Host: Eugene Kolomeisky]
Wednesday, April 27, 2011
7:00 PM
Physics Building, Room 203
Note special date.
Note special time.
Note special room.
Friday, April 22, 2011
4:00 PM
Physics Building, Room 204
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Friday, April 15, 2011
4:00 PM
Physics Building, Room 204
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"Elementary Particles of Superconductivity"
Assa Auerbach , Technion, Israel Institute of Technology
[Host: Israel Klich]
Thursday, April 7, 2011
7:00 PM
Chemistry , Room 402
Note special date.
Note special time.
Note special room.
"Beyond Smoke and Mirrors: Climate Change and Energy in the 21st Century"
Burton Richter , Stanford University
[Host: Brad Cox]
Professor Richter is the co-winner of the 1976 Nobel Prize in physics for the discovery of the J/Ψ particle which was the first observation of a particle containing a fourth quark named the charm quark and was a central part of the so-called November revolution of particle physics. He has accumulated many other honors in his career including a long tenure as the director of Stanford Linear Acceleratory Laboratory from 1984 to 1999. He has also been the recipient of the E.O. Lawrence Medal, has served as president of the American Physical Society, and is a member of the National Academy of Sciences. He presently serves on the board of directors of Scientists and Engineers for America, an organization focused on promoting sound science in American government and is a Senior Fellow by Courtesy of the Center for Environmental Science and Policy at Stanford Institute for International Studies. In the past several years Professor Richter has turned his attention to the central problem of the 21st century, the effect of human activity on the global climate. He has written a book with the same title as his lecture.
Friday, February 18, 2011
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Friday, February 11, 2011
4:00 PM
Physics Building, Room 204
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Note special room.
Tuesday, February 8, 2011
3:30 PM
Physics Building, Room 204
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Note special room.
"Top Quarks at the Large Hadron Collider: In Pursuit of Truth and its Consequences"
Chris Neu , University of Virginia
[Host: Joe Poon]
Friday, February 4, 2011
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Entanglement and Entropy in many body systems"
Israel Klich , University of Virginia
[Host: Joe Poon]
Friday, January 28, 2011
4:00 PM
Physics Building, Room 204
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Note special room.
Friday, January 21, 2011
4:00 PM
Physics Building, Room 204
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"Memristance and Negative Differential Resistance in Transition Metal Oxides"
Stan Williams , HP
[Host: Stu Wolf]
Friday, December 3, 2010
4:00 PM
Physics Building, Room 204
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Note special room.
Friday, November 19, 2010
4:00 PM
Physics Building, Room 204
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Note special room.
Friday, November 12, 2010
4:00 PM
Physics Building, Room 204
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Friday, November 5, 2010
4:00 PM
Physics Building, Room 204
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"GEM*STAR (Green Energy-Multiplier: Sub-critical, Thermal spectrum, Accelerator-driven, Recycling Reactor)"
Bruce Vogelaar , Virginia Tech
[Host: Blaine Norum]
The GEM*STAR approach to such an Accelerator Driven System (ADS) thus intrinsically breaks the links to issues which have crippled the nuclear energy option. It does this by requiring: no enrichment, no reprocessing, no critical-mass on site; and providing far deeper burning with orders-of-magnitude less releasable radioactivity in its core and resulting in far less final waste. The project will demonstrate electricity cheaper than coal, and could beneficially utilize today's LWR spent fuel producing no additional waste.
Results from the recent workshop on ADS (hosted by VT and JLab) along with the new report from the DOE will be presented. GEM*STAR is a project of ADNA Corp. and the Virginia GEM*STAR Consortium (VCU, VT, JLab, UVA).
Friday, October 29, 2010
4:00 PM
Physics Building, Room 204
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Note special room.
[1] P. W. Shor, “Algorithms for quantum computation: discrete logarithms and factoring,” in Proceedings, 35th Annual Symposium on Foundations of Computer Science, S. Goldwasser, ed., pp. 124–134 (IEEE Press, Los Alamitos, CA, Santa Fe, NM, 1994).
[2] R. P. Feynman, “Simulating Physics With Computers,” Int. J. Theor. Phys. 21, 467 (1982).
[3] J. L. Hall, “Nobel Lecture: Defining and measuring optical frequencies,” Rev. Mod. Phys. 78, 1279 (2006)
[4] T. W. Hänsch, “Nobel Lecture: Passion for precision,” Rev. Mod. Phys. 78, 1297 (2006).
[5] N. C. Menicucci, S. T. Flammia, and O. Pfister, “One-way quantum computing in the optical frequency comb,” Phys. Rev. Lett. 101, 130501 (2008).
[6] S. T. Flammia, N. C. Menicucci, and O. Pfister, “The optical frequency comb as a one-way quantum computer,” J. Phys. B, 42, 114009 (2009).
Friday, October 15, 2010
4:00 PM
Physics Building, Room 204
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Note special room.
Friday, October 8, 2010
4:00 PM
Physics Building, Room 204
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"Materials world under scrutiny: the view using a very powerful probe"
Despina Louca , University of Virginia
[Host: Joe Poon]
Friday, October 1, 2010
4:00 PM
Physics Building, Room 204
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Note special room.
"Science, Political Science, and Social Responsibility"
J.J. Suh and Seunghun Lee , Johns Hopkins University / University of Virginia
[Host: Seunghun Lee]
Friday, September 24, 2010
4:00 PM
Physics Building, Room 204
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Note special room.
"The Jefferson Lab Program on Inclusive and Semi-Inclusive Deep Inelastic Scattering"
Sebastian Kuhn , Old Dominion University
[Host: Don Crabb]
Friday, September 10, 2010
4:00 PM
Physics Building, Room 204
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Note special room.
"Beauty is only skin deep; probing thin film and membrane structure by neutron reflection"
Chuck Majkrzak , NIST
[Host: Seunghun Lee]
Friday, April 30, 2010
4:00 PM
Physics Building, Room 204
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Note special room.
"The Search for the Heisenberg-Schwinger Effect: Nonperturbative Pair Production from Vacuum"
Gerald Dunne , University of Connecticut
[Host: Israel Klich]
Friday, April 16, 2010
4:00 PM
Physics Building, Room 204
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Note special room.
"Applied string theory -- from gravitational collapse to quark-gluon liquids"
Paul Chesler , M.I.T.
[Host: Peter Arnold]
Friday, March 26, 2010
4:00 PM
Physics Building, Room 204
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Note special room.
"Casimir effect due to a single boundary as a manifestation of the Weyl problem"
Genya Kolomeisky , University of Virginia
[Host: Dinko Pocanic]
Friday, March 19, 2010
4:00 PM
Physics Building, Room 204
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Friday, March 5, 2010
4:00 PM
Physics Building, Room 204
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"The Race for the Higgs Boson
(A Tevatron Perspective)"
R. Craig Group , Fermilab
[Host: Craig Dukes]
Monday, March 1, 2010
3:30 PM
Physics Building, Room 204
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Note special room.
"Low-Background Searches for Rare Events: The MAJORANA Neutrinoless Double-Beta Decay Experiment, and the CLEAN/DEAP Dark Matter Search"
Victor Gehman , Los Alamos National Laboratory
[Host: Craig Dukes]
Friday, February 26, 2010
4:00 PM
Physics Building, Room 204
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Note special room.
Wednesday, February 24, 2010
3:30 PM
Physics Building, Room 204
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Note special room.
"The MuLan Experiment: Measuring the Muon Lifetime to 1ppm"
Kevin Lynch , Boston University
[Host: Craig Dukes]
Tuesday, February 23, 2010
3:30 PM
Physics Building, Room 204
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Note special room.
Wednesday, February 17, 2010
3:30 PM
Physics Building, Room 204
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Note special room.
"Searches for a Standard Model Higgs Boson at the Collider Detector at Fermilab"
Jennifer Pursley , University of Wisconsin
[Host: Craig Dukes]
Friday, February 12, 2010
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Novel magnetism in ultracold atomic gases"
Austen Lamacraft , University of Virginia
[Host: Dinko Pocanic]
Friday, January 29, 2010
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Wednesday, January 27, 2010
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
Friday, January 22, 2010
4:00 PM
Physics Building, Room 204
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"Why does the (free) neutron decay (?)"
Stefan Baessler , University of Virginia
[Host: Dinko Pocanic]
Friday, December 4, 2009
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Meeting Future Energy Demand Through Unconventional Technology "
Kambiz Safinya , Schlumberger Research
[Host: Tom Gallagher]
Friday, November 13, 2009
4:00 PM
Physics Building, Room 204
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Note special room.
Friday, November 6, 2009
4:00 PM
Physics Building, Room 204
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"Detecting Gravitational Waves (and doing other cool physics) with Millisecond Pulsars"
Scott Ransom , NRAO
[Host: PQ Hung]
Friday, October 30, 2009
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Nonequilibrium thermodynamics at the microscale"
Christopher Jarzynski , Univ. of Maryland
[Host: Austen Lamacraft]
Friday, October 23, 2009
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Nanotube & Graphite based electronics"
Keith Williams , University of Virginia
[Host: Dinko Pocanic]
Friday, October 16, 2009
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Entropy in Quantum Information Theory and Condensed Matter Physics"
Matthew Hastings , Station Q, UCSB
[Host: Israel Klich]
Friday, October 9, 2009
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Friday, September 25, 2009
4:00 PM
Physics Building, Room 204
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Friday, September 18, 2009
4:00 PM
Physics Building, Room 204
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"Exploring the Nature of Matter: Jefferson Lab and its plans"
Hugh Montgomery , Director of JLab
[Host: Gordon Cates]
Friday, September 4, 2009
4:00 PM
Physics Building, Room 204
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Note special room.
" E = mc^2, High energy and intensity opens windows on the world"
Young-kee Kim , Deputy Director, Fermilab/University of Chicago
[Host: Seunghun Lee]
Friday, May 1, 2009
4:00 PM
Physics Building, Room 204
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Note special room.
"Superconductivity at the Dawn of the Iron Age"
Zlatko Tesanovic , Johns Hopkins University
[Host: Seunghun Lee]
Friday, April 24, 2009
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Academic Fraud and a Calculus of Death"
George Gollin , University of Illinois
[Host: Craig Dukes ]
Friday, April 17, 2009
4:00 PM
Physics Building, Room 204
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Note special room.
Friday, April 10, 2009
4:00 PM
Physics Building, Room 204
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"Non-Abelian anyons: New particles for less than a billion"
Kirill Shtengel , UC Riverside
[Host: Israel Klich]
Friday, April 3, 2009
4:00 PM
Physics Building, Room 204
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Note special room.
"High Temperature Superconductivity - After 23 years, where are we at? "
Mike Norman , Argonne National Laboratory
[Host: Despina Louca]
Friday, March 27, 2009
4:00 PM
Physics Building, Room 204
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"Quantum Manipulation of Neutral Atoms Without Forces"
Thad Walker , University of Wisconsin
[Host: Tom Gallagher]
Friday, March 20, 2009
4:00 PM
Physics Building, Room 204
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Note special room.
"Beyond E=mc^2: Using Rare Particle Decays to Probe the Energy Frontier"
Craig Dukes , University of Virginia
[Host: Jongsoo Yoon]
Thursday, March 12, 2009
2:00 PM
MEC, Room 205
Note special date.
Note special time.
Note special room.
Friday, February 20, 2009
4:00 PM
Physics Building, Room 204
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"FRIB: A New Accelerator Facility for the Production of Radioactive Beams"
Richard York , MSU
[Host: Blaine Norum]
Friday, February 13, 2009
4:00 PM
Physics Building, Room 204
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Friday, February 6, 2009
4:00 PM
Physics Building, Room 204
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"Studying strong and electroweak interactions using electron scattering at Jefferson Lab"
Xiaochao Zheng , University of Virginia
[Host: Dinko Pocanic]
Friday, January 23, 2009
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"The Quantum Spin Hall Effect and Topological Band Theory"
Charlie Kane , U. Penn
[Host: Israel Klich]
Friday, December 5, 2008
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"The study of neutron quantum states in the Earth's gravitational field"
Stefan Baessler , University of Virginia
[Host: Dinko Pocanic]
Friday, November 21, 2008
4:00 PM
Physics Building, Room 204
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Note special room.
Friday, November 14, 2008
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Friday, November 7, 2008
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Quantum-limited measurements: One physicist's crooked path from quantum optics to quantum information"
Carl Caves , University of New Mexico
[Host: Olivier Pfister]
Friday, October 31, 2008
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"SCIENTIFIC CHALLENGES IN HYDROGEN STORAGE: BREAKTHROUGHS AT UVa"
Bellave Shivaram , University of Virginia
[Host: Jongsoo Yoon]
Thursday, October 30, 2008
4:00 PM
Physics Building, Room 204
Note special date.
Note special time.
Note special room.
"Magnetic field-induced phase transition in a quantum gapped system: is the Bose-Einstein condensation concept useful?"
Seunghun Lee , University of Virginia
[Host: Dinko Pocanic]
Friday, October 24, 2008
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Physics –Fundamentals for Business"
Mark Adams , Vice President, ITT Corporation
[Host: Bascom Deaver]
Friday, October 17, 2008
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Bending Back the Light: The science of negative refraction"
Costas Soukoulis , Ames Lab
[Host: Michael Fowler]
Friday, October 3, 2008
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Detecting Cosmic Messengers with Antarctic Balloon Flights "
Eun-Suk Seo , University of Maryland
[Host: Seunghun Lee]
Friday, September 26, 2008
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"The Ancient Science of Violinmaking"
Oded Kishony , Charlottesville, Violinmaker
[Host: Keith Williams]
Friday, September 12, 2008
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Friday, September 5, 2008
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Photon Wave Mechanics and Spin-Orbit Interaction in Single Photons"
Michael Raymer , University of Oregon
[Host: Olivier Pfister]
Friday, April 25, 2008
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Interaction between a molecular magnet monolayer and a metallic surface"
Kyungwha Park , Virginia Tech
[Host: Keith Williams]
Friday, April 18, 2008
4:00 PM
Physics Building, Room 203
Note special time.
Note special room.
"Is the search for the origin of the highest energy cosmic rays over?"
Alan Watson , Leeds University, England
[Host: Brad Cox]
This question can now be asked because of two results obtained using data recorded at the Pierre Auger Observatory. It has been established, at the 6-sigma level, that the flux of the highest energy cosmic rays is suppressed at energies beyond 5 x 10 19 eV and that above this energy an anisotropy in the arrival directions of the particles is apparent. The arrival directions appear to be associated with sources within the GZK horizon (z ~ 0.018 or 75 Mpc). From these observations it seems probable that we have observed the long-sought Greisen-Zatsepin-Kuzmin effect, demonstrating that ultra-high energy cosmic rays are of extragalactic origin. It is also probable that these particles are protons, thus offering the possibility of insights into features of particle physics at centre-of-mass energies 30 times greater than will be reached at the LHC. Preliminary conclusions from studies of detailed features of extensive air showers suggest that extrapolations from Tevatron energies may not be what have been anticipated hitherto. Much further work remains to be done.
Thursday, April 17, 2008
7:30 PM
Physics Building, Room Chemistry Building, Room 402
Note special date.
Note special time.
Note special room.
"The Birth of Cosmic Ray Astronomy on the Argentine Pampas"
Alan Watson , University of Leeds, United Kingdom
[Host: Physics Department]
Tuesday, April 15, 2008
4:00 PM
Physics Building, Room 204
Note special date.
Note special time.
Note special room.
Friday, April 11, 2008
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Nucleon Form Factors...50 Years Later"
John Arrington , Argonne National Lab
[Host: Nilanga Liyanage]
Monday, April 7, 2008
4:00 PM
Wilsdorf Hall, Room Atrium
Note special date.
Note special time.
Note special room.
Friday, March 28, 2008
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Friday, February 22, 2008
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Wednesday, February 20, 2008
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
"W Bosons and b Quarks at the Tevatron: Understanding the Haystack to Help Find the Needle"
Christopher Neu , University of Pennsylvania
[Host: Brad Cox]
Tuesday, February 19, 2008
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
Friday, February 15, 2008
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"A More Accurate Measurement of Pion to Positron Decay"
Marvin Blecher , Virginia Tech
[Host: Blaine Norum]
Wednesday, February 13, 2008
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
"Searching for Physics Beyond the Standard Model with Neutrinos"
Zelimir Djurcic , Columbia University
[Host: Brad Cox]
Friday, February 8, 2008
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Life, the Universe, and Electroweak Symmetry Breaking"
Andrew Askew , Florida State University
[Host: Brad Cox]
Friday, January 25, 2008
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Protein Folding: Energy, Entropy, and Prion Diseases"
Bernard Gerstman , Florida International University
[Host: Art Brill]
Friday, December 7, 2007
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"The Deep Puzzle of High-Temperature Superconductivity"
T. Egami , University of Tennessee
[Host: Despina Louca]
Friday, November 16, 2007
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Designer atoms: Engineering Rydberg atom wavepackets using pulsed electric fields "
Barry Dunning , Rice University
[Host: Tom Gallagher]
Friday, November 9, 2007
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Friday, November 2, 2007
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Friday, October 26, 2007
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Measurement of the π 0 Lifetime: Probing the QCD Axial Anomaly"
Aron Bernstein , Massachusetts Institute of Technology
[Host: Dinko Pocanic]
Friday, October 19, 2007
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Creating a Quark Gluon Plasma with Heavy Ion Collisions"
David Hofman , University of Illinois Chicago
[Host: Bob Hirosky ]
Friday, October 5, 2007
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Natural Nuclear Reactor in Oklo"
Alex Meshik , Washington University, St. Louis
[Host: Keith Williams]
Friday, September 28, 2007
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Interplay of disorder and interactions in two dimensions"
Sergey Kravchenko , Northeastern University
[Host: Joe Poon]
Friday, September 21, 2007
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"JLab Scientific and Technological Advances with Commonwealth of Virginia Universities"
Ganapati Myneni , JLab
[Host: Bellave Shivaram]
Friday, September 14, 2007
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"A Century of Photo Physics: Mitchell Memorial Colloquium"
Keith Williams , University of Virginia
[Host: Genya Kolomeisky]
Friday, August 31, 2007
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Wednesday, April 25, 2007
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
"Strongly-Coupled Plasmas and Gauge/String Duality"
Larry Yaffe , University of Washington
[Host: Peter Arnold]
Friday, April 20, 2007
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"An Ultrafast Quantum Camera - Observing and Controlling Molecular Dynamics in Real Time"
Thomas Weinacht , SUNY Stony Brook
[Host: Bob Jones]
Friday, April 13, 2007
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"The CMS Experiment at the CERN Large Hadron Collider"
Dr Daniel Green , Fermi National Accelerator Lab
[Host: Brad Cox]
Friday, April 6, 2007
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"A New Search on Neutron Electric Dipole Moment"
Haiyan Gao , Duke University
[Host: Simonetta Liuti]
Friday, March 30, 2007
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Friday, March 23, 2007
4:00 PM
Physics Building, Room 203
Note special time.
Note special room.
"From the Big Bang to the Nobel Prize and Beyond"
John Mather , Goddard Space Flight Center
[Host: Brad Cox]
The Cosmic Background Explorer (COBE) satellite, proposed in 1974 and launched by NASA in 1989, measured the cosmic microwave and infrared background radiation from the Big Bang and everything that happened later. The COBE team made three key measurements: the spectrum of the cosmic microwave background radiation (CMBR) matches a blackbody within 50 ppm (rms), the CMBR is anisotropic, with 10 ppm variations on a 7o angular scale, and the cosmic infrared background from previously unknown objects is as bright as all the known classes of galaxies. The first measurement confirmed the Hot Big Bang theory with unprecedented accuracy, the second is interpreted as representing quantum mechanical fluctuations in the primordial soup and the seeds of cosmic structure and the basis for the existence of galaxies, and the third is still not fully understood. I will describe the project history, the team members, the hardware and data processing, the major results, and their implications for science, and end with the outlook for future progress with new background measurements and large telescopes such as the James Webb Space Telescope. I will show recent progress on building the JWST, with illustrations of the key technologies.
Friday, March 16, 2007
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Quantum simulations and quantum computation with atoms in optical lattices"
David Weiss , Penn State University
[Host: Tom Gallagher]
Friday, March 2, 2007
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Friday, February 16, 2007
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"The Evolution from BCS to Bose-Einstein Condensation: Superfluidity in Metals, Neutrons Stars, Nuclei, and Ultra-Cold Atoms"
Carlos Sa de Melo , Georgia Tech
[Host: Joe Poon]
Friday, February 9, 2007
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Molecular Electronics- Past, Present and Future"
Keith Williams , University of Virginia
[Host: Dinko Pocanic]
Friday, February 2, 2007
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"New magnetic twists for multiferroicity"
Sang-Wook Cheong , Rutgers University
[Host: Seunghun Lee]
Friday, January 19, 2007
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"New Ideas in Neutrino Physics"
Dan Kaplan , Illinois Institute of Technology
[Host: E. Craig Dukes]
Friday, November 24, 2006
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Friday, November 17, 2006
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Searching for the mechanism of electroweak symmetry breaking"
Csaba Csaki , Cornell University
[Host: P.Q. Hung]
Friday, November 3, 2006
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Potential Room Temperature Superconductivity in Metallic Nanoclusters"
Vladimir Kresin , LBL
[Host: Stu Wolf]
Friday, October 27, 2006
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Conditional measurements in cavity QED"
Luis Orozco , University of Maryland
[Host: Olivier Pfister]
Tuesday, October 24, 2006
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
"Almost everything that you'd like to know about frustrated magnets"
Seunghun Lee , University of Virginia
[Host: Dinko Pocanic]
Monday, October 23, 2006
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
"Magnetically induced electronic states in two-dimensional superconductors"
Jongsoo Yoon , University of Virginia
[Host: Dinko Pocanic]
Friday, October 20, 2006
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"The Plasma Physics of Quark-Gluon Plasma (a theorist's perspective)"
Peter Arnold , University of Virginia
[Host: Dinko Pocanic]
Tuesday, October 17, 2006
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
"Jefferson Lab Hall: A neutron spin structure program"
Nilanga Liyange , University of Virgina
[Host: Dinko Pocanic]
Monday, October 16, 2006
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
"An Atom Interferometer Using Bose-Einstein"
Cass Sackett , University of Virginia
[Host: Dinko Pocanic]
Friday, October 13, 2006
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
""A Bose Condensate in an Optical Lattice: cold atoms meet solid state""
Bill Phillips , NIST
[Host: Thomas Gallagher]
Friday, October 6, 2006
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Nonclassical Light and Glauber's Theory of Optical Coherence"
Howard Carmichael , University of Auckland, New Zealand
[Host: Olivier Pfister]
Friday, September 29, 2006
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"The National Science Foundation, One Particle Physicist's Experience"
Randy Ruchti , Notre Dame University and NSF
[Host: Brad Cox]
Friday, September 22, 2006
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Friday, September 15, 2006
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"The Unusual Symmetry of Ferroelectricity in Incommensurate Magnets"
Brooks Harris , University of Pennsylvania
[Host: Seunghun Lee]
Friday, September 8, 2006
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"The Ocean Tides: Myth and Truth from Galileo to GPS"
Vittorio Celli , University of Virginia
[Host: Steve Thornton]
Tuesday, May 9, 2006
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
"Experiments With Polarized 3He at the Mainz Microtron (MAMI)"
Daniela C. Rohe , University of Basel, Switzerland
[Host: Nilanga Liyanage]
In this talk I will discuss polarized target technology and will explain the technique and installation used to polarize 3He for the nuclear physics target at MAMI. The emphasis of the talk is on the results achieved so far at MAMI with polarized 3He. Their purpose is twofold: To test the reliability of the theoretical description of 3He and to measure the electric form factor of the neutron. An outlook about ongoing and future research will be given.
Thursday, May 4, 2006
3:00 PM
Physics Building, Room 205
Note special date.
Note special time.
Note special room.
"What Have We Learned from Polarized Deep Inelastic Scattering?"
Xiaochao Zheng , MIT
[Host: Nilanga Liyanage]
I will start from an introduction to the study of hadron structure using lepton deep inelastic scattering and give an overview of world data and what we have already learned about nucleon structure. Then I will present results from a precision experiment completed at Jefferson Lab on the neutron spin in the valence quark region, and discuss about the future of this measurement.
The last 10 minutes of the talk will be devoted to a different topic: using polarized electron scattering to test the electro-weak Standard Model and hadronic structure, and introducing the PV-DIS program that is being just launched at Jefferson Lab.
The talk will be given on an non-expert level.
Monday, May 1, 2006
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
"Using Parity Violation to Probe Strange Quarks in the Nucleon"
Kent Paschke , University of Massachusetts
[Host: Nilanga Liyanage]
Friday, April 28, 2006
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"The Design, Growth, Discovery and Characterization of Novel Intermetallic Compounds"
Paul C. Canfield , Ames Laboratory and Department of Physics and Astronomy, Iowa State University
[Host: Seung-Hun Lee]
Tuesday, April 25, 2006
3:30 PM
Physics Building, Room 204
Note special date.
Note special room.
"Can Quarks in a Polarized Nucleon Tell Left from Right ?"
Xiaodong Jiang , Rutgers University
[Host: Nilanga Liyanage]
Friday, April 21, 2006
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Recent Results and Future Prospects in Neutrino Physics"
Peter Shanahan , Fermi National Accelerator Laboratory
[Host: Brad Cox]
Friday, April 14, 2006
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Friday, April 7, 2006
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Nucleon Structure Studies with Polarized Photons and Polarized Nucleons"
Oscar Rondon-Aramayo , UVA
[Host: Genya Kolomeisky]
Friday, March 31, 2006
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Friday, March 24, 2006
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Friday, March 17, 2006
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"The MESSENGER Mission to Mercury: Science and Status"
Ralph McNutt , Johns Hopkins University
[Host: Blaine Norum]
Friday, March 3, 2006
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Friday, February 24, 2006
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Friday, February 17, 2006
4:00 PM
Physics Building, Room 203
Note special time.
Note special room.
"Preliminary Results on the Nature of the Dark Energy from the ESSENCE Supernova Survey "
Christopher Stubbs , Harvard University
[Host: Brad Cox]
Friday, February 3, 2006
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Exploding Stars, Neutrinos, and Nucleosynthesis"
Gail McLaughlin , North Carolina State University
[Host: Steve Thornton]
Friday, January 20, 2006
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Nuclear Spin-Electron Spin Interactions in the Three-Atom System H2N"
Art Brill , UVA
[Host: Genya Kolomeisky]
Friday, December 2, 2005
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Physics and the CMS Detector at the CERN Large Hadron Collider"
Roger Rusach , University of Minnesota
[Host: Brad Cox]
Friday, November 18, 2005
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Friday, November 11, 2005
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Oxide-Semiconductor Materials for Quantum Computation"
Jeremy Levy , University of Pittsburgh
[Host: Joe Poon]
Friday, November 4, 2005
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Probing the Geodynamo"
Peter Olson , John Hopkins University - Earth and Planetary Sciences
[Host: Keith Williams]
Friday, October 28, 2005
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Clusters: a route to study stability at nanometer scale"
Catherine Brechnigac
[Host: Thomas Gallagher]
Friday, October 21, 2005
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"The Importance of Spin in Particle Physics"
Gary Goldstein , Tufts University
[Host: Simonetta Liuti ]
Friday, October 7, 2005
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Friday, September 30, 2005
4:00 PM
Physics Building, Room 203 font>
Note special time.
Note special room.
Friday, September 23, 2005
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Friday, September 16, 2005
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Charge Particle Radiography for National Security"
Chris Morris , Los Alamos National Laboratory
[Host: Craig Dukes]
Friday, September 9, 2005
4:00 PM
Physics Building, Room 203
Note special time.
Note special room.
"Understanding The Columbia Shuttle Accident and NASA's Challenges Posed by Discovery"
Doug Osheroff , Stanford University
[Host: Craig Dukes]
Thursday, September 8, 2005
4:00 PM
Physics Building, Room 204
Note special date.
Note special time.
Note special room.
"The Spallation Neutron Source: A Powerful Tool for Materials Research"
Thom Mason , Director, Spallation Neutron Source - Oak Ridge National Laboratory
[Host: Seunghun Lee]
[Coffee will be served in Room 205 at 3:30 PM]
Tuesday, May 31, 2005
4:00 PM
Physics Building, Room 204
Note special date.
Note special time.
Note special room.
"Towards a Quantum Laboratory on a Chip"
Professor Theodor Hansch , Max Planck Institute for Quantum Optics
[Host: Thomas Gallagher]
Friday, May 6, 2005
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Tidbits About Qubits: Spin Computation in Nanostructures"
Sankar Das Sarma , University of MarylandCondensed Matter Theory Center -
[Host: Keith Williams]
Friday, April 29, 2005
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Friday, April 22, 2005
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"The Asymmetry Between Matter and Anti Matter - or -How to Know if it is Safe to Shake an Alien's Hand?"
Klaus Hon , Ohio State University
[Host: Brad Cox]
Friday, April 15, 2005
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"The Search For the Exotic 5 Quark Baryons"
Marco Mirazita , INFN, Laboratori Nazionali di Frascati
[Host: Simonetta Liuti]
Friday, April 8, 2005
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Production of Microscopic Black Holes by Cosmic Rays"
Al Shapere , University of Kentucky
[Host: Paul Fendley]
Thursday, April 7, 2005
4:00 PM
Physics Building, Room 204
Note special date.
Note special time.
Note special room.
Friday, April 1, 2005
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"High-Temperature Superfluidity in Ultra-Cold Fermi Gases"
J. E. Thomas , Duke University
[Host: Thomas Gallagher]
Friday, March 25, 2005
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Planetary Models From the Middle Ages"
E. Paschos , University of Dortmund, Germany
[Host: Brad Cox]
Friday, February 18, 2005
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Acoustic Inertial Confinement Nuclear Fusion - Status and Challenges"
Rusi P. Taleyarkhan , The Purdue University
[Host: Craig Dukes]
Friday, February 11, 2005
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"NANOMACHINES: From Atomic Lattice Gears to Cystic Fibrosis"
Rich Superfine , University of North Carolina
[Host: Keith Williams]
Friday, February 4, 2005
4:00 PM
Physics Building, Room 203
Note special time.
Note special room.
"Life, the Universe, and Nothing: The Future of Life in an Ever-Expanding Universe"
Lawrence Krauss , Case Western Reserve University
[Host: P.Q. Hung]
Friday, January 21, 2005
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Photon-ion Collisions and Molecular Clocks"
C. L. (Lew) Cocke , Kansas State University
[Host: Tom Gallagher]
Friday, December 3, 2004
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Gravitational Waves as a Tool to Investigate Neutron Star Structure"
Alessandro Drago , Universita' degli Studi di Ferrara
[Host: Simonetta Liuti]
Friday, November 19, 2004
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Electronic Liquid Crystals: Novel Phases of Electrons in Two Dimensions"
Alan Dorsey , University of Florida
[Host: Michael Fowler]
Friday, October 29, 2004
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Friday, October 22, 2004
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Hidden Dimensionality in Frustrated Magnets and Complex Superconductors"
Joel Moore , Berkeley
[Host: Paul Fendley]
Friday, October 15, 2004
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"The Science and Sociology of Pentaquarks"
Thomas Cohen , University of Maryland
[Host: Simonetta Liuti]
Friday, October 8, 2004
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"A Physicist Approach to Complex Problems"
Professor Shmuel Nussinov , Tel Aviv University
[Host: P.Q. Hung]
Friday, October 1, 2004
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Friday, September 24, 2004
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"New Opportunities in Neutrino Oscillation Physics"
Milind Diwan , Brookhaven National Lab
[Host: Brad Cox]
Friday, September 10, 2004
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Primal Scream- Sounds From the Infant Universe"
Mark Whittle , University of Virginia Astronomy
[Host: Peter Arnold]
Friday, April 23, 2004
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"The Dilute, Cold Bose Gas: A truly quantum-mechanical many-body problem"
Elliott Lieb , Princeton University
[Host: E. Kolomeisky]
Friday, April 16, 2004
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Unraveling the mysteries in complex oxides by neutron scattering"
Seunghun Lee , National Institute of Standards and Technology
[Host: Joe Poon]
Friday, April 2, 2004
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Friday, March 19, 2004
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"High Energy Physics - On the Ground, Underground, and in Space"
Dr. Kathleen Turner , Dept of Energy, Office of Science, Office of High Energy Physics
Friday, March 5, 2004
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Quantum Computers and Atom-Scale Electronics in Silicon"
John R. Tucker , Department of Electrical and Computer Engineering - University of Illinois at Urbana-Champaign
[Host: Olivier Pfister]
Friday, February 20, 2004
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Friday, February 13, 2004
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Measuring the Information Velocity in Fast- and Slow-Light Media"
Daniel J. Gauthier , Duke University - Fitzpatrick Center for Photonics and Communication Systems
[Host: Olivier Pfister]
Friday, February 6, 2004
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Friday, January 30, 2004
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Precision exploration of neutron spin structure at Jefferson Lab Hall A"
Nilanga Liyanage , UVA
[Host: Tom Gallagher]
Friday, January 23, 2004
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Fun with Fermions: Exploring and Manipulating a Fermi Gas of Atoms"
Debbie Jin , Univ. of Colorado
[Host: Thomas Gallagher]
Friday, January 16, 2004
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Superconductors of a Different Stripe: Charge Inhomogeneity and Superconductivity in Copper Oxides"
John Tranquada , Brookhaven National Lab.
[Host: D. Louca]
Friday, December 5, 2003
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Conditional Dynamics and quantum feedback; an experiment in cavity QED"
Luis Orozco , U. of Maryland
[Host: Olivier Pfister]
Friday, November 21, 2003
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
REFERENCES
1. Y. Qiu, C. Broholm, S. Ishiwata, M. Azuma, M. Takano, R. Bewley, and W. J. L. Buyers, cond-mat/0205018.
2. Guangyong Xu, J. F. DiTusa, T. Ito, H. Takagi, K. Oka, C. Broholm and G. Aeppli, Phys. Rev. B 54, R6827 (1996).
3. M. B. Stone, I. A. Zaliznyak, Daniel H. Reich, and C. Broholm, Phys. Rev. B 64, 144405 (2001).
4. M. B. Stone, J. Rittner, Y. Chen, H. Yardimci, D. H. Reich, C. Broholm, D. V. Ferraris, and T. Lectka, Phys. Rev. B 65, 064423 (2002).
5. M. Kenzelmann, G. Xu, I. A. Zaliznyak, C. Broholm, J. F. DiTusa, G. Aeppli, T. Ito, K. Oka, and H. Takagi. Phys. Rev. Lett. 90, 087202 (2003).
6. Y. Chen, Z. Honda, A. Zheludev, C. Broholm, K. Katsumata, and S. M. Shapiro Phys. Rev. Lett. 86, 1618 (2001).
Friday, November 14, 2003
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"The BEC transition temperature of dilute gases: a not-so-simple problem in statistical mechanics"
Peter Arnold , UVA
[Host: E. Kolomeisky]
Friday, November 7, 2003
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Entangled Photons for Quantum Information: 101 uses for a Schroedinger cat"
Paul Kwiat , U of Illinois, Urbana-Champaign
[Host: Olivier Pfister]
Friday, October 24, 2003
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"A new spin on electronics - spintronics"
Dr. Stuart A. Wolf , University of Virginia, and DARPA at Arlington, VA
[Host: Joe Poon and James Groves]
Friday, October 17, 2003
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Friday, October 10, 2003
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"The Quantum Hall Bilayer: A New Superfluid"
Herb Fertig , University of Kentucky
[Host: E. Kolomeisky]
Friday, September 12, 2003
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Envisioning Particles and Interactions"
Professor Chris Quigg , Fermi National Accelerator Laboratory
[Host: Brad Cox]
Friday, April 25, 2003
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"How a doctor of particle physics found happiness working with 'real doctors'"
Prof. John Malko , Emory University
[Host: Oscar Rondon]
Friday, April 18, 2003
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Friday, April 11, 2003
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Nanotechnology, nanotubes and molecules as tinker toys"
Sean Washburn , University of North Carolina at Chapel Hill
[Host: Joseph Poon]
Friday, April 4, 2003
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"The Fascination of Neutrino Oscillations: Their discovery and their future study"
Leslie Camilleri , Fermilab/CERN
[Host: Craig Dukes]
Friday, March 21, 2003
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Interactions and Disorder in Quantum Dots: A New Large-g Approach"
Ganpathy Murthy , University of Kentucky
[Host: Eugene Kolomeisky]
Friday, March 14, 2003
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"A new look at rare pion and muon decays"
Dinko Pocanic , University of Virginia
[Host: Eugene Kolomiesky]
In its first phase, the PIBETA experiment has measured accurately several such rare decays at PSI, the Swiss meson facility. The talk will focus on the motivation, experimental apparatus, method, and the unexpected first results of these measurements.
Friday, February 21, 2003
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Friday, February 14, 2003
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Nuclear Spin Relaxation, Dispersion, and Intermolecular Exploration"
Robert Bryant , UVA - Chemistry
[Host: Bascom Deaver]
Friday, February 7, 2003
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Experimental evidence for hadronic deconfinement in pbar-p collisions at 1.8 TeV"
Rolf Sharenberg , Purdue University - (E-735 Collaboration)
[Host: Ken Nelson]
Friday, January 31, 2003
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Gender and Physics: a Hard Look at a Hard Science"
Amy Bug , Swarthmore College
[Host: Simonetta Liuti]
Friday, January 24, 2003
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Friday, November 22, 2002
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Tabletop probes for TeV physics: searches for the electric dipole moment of the electron"
David DeMille , Yale
[Host: Cass Sackett]
Friday, November 15, 2002
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
" 0.7-anomaly in Quantum Point Contacts A"
Konstantin Matveev , Duke University
[Host: Eugene Kolomeisky]
Friday, November 8, 2002
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Physics at DZERO: Exploring the Microscopic Structure of the Universe"
Jerry Blazey , NIU
[Host: Bob Hirosky]
Friday, October 25, 2002
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Tunable Interactions in Ultracold Bose and Fermi Gases - Solitons to Superfluids"
Randy Hulet , Rice University
[Host: Cass Sackett]
Friday, October 18, 2002
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Superconducting Schrodingers Cat and its Application to Quantum Computing"
Siyuan Han , Department of Physics and Astronomy, University of Kansas
[Host: B. Shivaram]
Friday, October 4, 2002
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Global Data Grids for Data Intensive Science"
Professor Paul Avery , University of Florida
[Host: Brad Cox]
Friday, September 20, 2002
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Friday, September 13, 2002
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"The Role of Clusters in the Design of Nano-Scale Systems"
Prof. Puru Jena , Virginia Commonwealth University
[Host: Joseph Poon/Louis Bloomfield]
Friday, April 26, 2002
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"A Singular Potential:from Theorist's Toy to Experimental Realization"
Sidney A. Coon , NSF and New Mexico State University
[Host: S. Liuti]
Friday, April 19, 2002
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Building Nucleons and Nuclei from Quarks and Glue: Early Results from the Research Program at Jefferson Lab"
Larry Cardman , JLab
[Host: T. Gallagher]
Friday, April 12, 2002
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Spontaneous evolution from a cold Rydberg gas to an ultra cold plasma"
Thomas Gallagher , University of Virginia
[Host: Eugene Kolomeisky]
Friday, March 29, 2002
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Long baseline neutrino oscillation experiments: why and how"
A. Marchionni , Fermi Lab
[Host: S. Conetti]
Friday, March 22, 2002
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"High-performance dielectric thin films for science and technology"
Dr. Bruce Van Dover , Agere Systems , Murray Hill NJ
[Host: Joseph Poon]
Friday, March 8, 2002
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Running Out of Time: Why Elephants Don't Gallop"
Julian Noble , University of Virginia
[Host: E. Kolomeisky]
1. An animal's strength/weight ratio decreases with size, hence a sufficiently large animal will be liable to injury if it attempts a gallop.
2. The time required for an animal to move its limbs increases with size, but the time an animal can remain in the air (while running) does not scale with linear dimension. Therefore there is some size beyond which an animal has "run out of time" and cannot take advantage of a running gait. These aspects of the biomechanics of locomotion bear on the interesting questions of determining the speeds of extinct species, as well as how varying gravity affects locomotion.
Friday, March 1, 2002
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Physicists and Industry in the 21st Century: Who, What, How"
N.O. Lipari , Lipari Int'l Consulting
[Host: V. Celli]
Friday, February 22, 2002
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"New States of Matter in the Quantum Hall and BEC Regimes "
Kareljan Schoutens , University of Amsterdam
[Host: Paul Fendley]
Friday, February 15, 2002
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Lattice Effects and Jahn-Teller Fluctuations in Crystals"
Despina Louca , University of Virginia
[Host: T. Gallagher]
Friday, February 8, 2002
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Friday, February 1, 2002
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Friday, January 25, 2002
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Quantum information with quantum fields: creation and entanglement of twin beams of light"
Olivier Pfister , University of Virginia
[Host: T. Gallagher]
Friday, January 18, 2002
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Optically probing and controlling a single quantum dot"
Daniel Gammon , Naval Research Lab.
[Host: O. Pfister]
Friday, December 7, 2001
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"New Dimensions in Probing the Structure and Function of Matter: Concepts, Techniques and Technologies"
Swapan Chattopadhyay , JLAB
[Host: Donal Day]
Friday, November 30, 2001
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Friday, November 16, 2001
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Friday, November 9, 2001
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"The Long Way From Strings To Large Extra Dimensions "
Mariano Quiros , Istituto de Estructura de la Materia (CSIC), Madrid, Spain
[Host: P. Q. Hung]
Friday, November 2, 2001
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Building a quantum computer atom by atom"
Chris Monroe , University of Michigan
[Host: Robert Jones]
Monday, October 29, 2001
7:30 PM
Chemistry Building , Room 402
Note special date.
Note special time.
Note special room.
"The Universe of the Elementary Particles"
Gerald 't Hooft , University of Utrecht
[Host: Department of Physics]
Friday, October 26, 2001
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"How does God Play Dice?
(Speculations about Quantum Mechanics at the Planck scale)"
G. 't Hooft , University of Utrecht, Netherlands
[Host: P. K. Kabir]
Friday, October 19, 2001
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Friday, October 12, 2001
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Understanding Flight"
David F. Anderson , Fermi National Accelerator Laboratory
[Host: Craig Dukes]
Friday, October 5, 2001
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Hyperfine physics - from the hydrogen atom to hemoglobin"
Arthur S. Brill , University of Virginia
[Host: E. Kolomeisky]
Friday, September 28, 2001
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"From the QCD Phase Diagram to Heavy Ion Collisions and Back"
Krishna Rajagopal , MIT
[Host: Peter Arnold]
Friday, September 21, 2001
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Friday, September 14, 2001
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"TheRole of Clusters in the Design of Nano-Scale Systems"
Puru Jena , Virginia Commonwealth University , Richmond, VA - Department of Physics
[Host: Lou Bloomfield and Joe Poon]
Friday, September 7, 2001
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"A Problem in Atmospheric physics: Stratospheric ozone depletion"
J. Elkins , National Oceanic and Atmospheric Administration
[Host: T. Gallagher]
Friday, May 11, 2001
11:00 AM
Physics Building, Room 204
Note special time.
Note special room.
"A Study of Atmospheric Neutrinos with the Super-Kamiokande Detector"
Professor James Stone , Boston University and Department of Energy
[Host: Robert Jones]
Friday, May 4, 2001
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Thursday, May 3, 2001
4:00 PM
Physics Building, Room 204
Note special date.
Note special time.
Note special room.
"Formation and Trapping of Ultracold Molecules by Photoassociation"
Pierre Pillet , Laboratoire Aime Cotton
[Host: Thomas Gallagher]
Friday, April 27, 2001
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"The Baryon Junction and High-Energy Nuclear Collisions"
Brian Cole , Columbia University
[Host: C. Dukes]
Friday, April 20, 2001
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Friday, March 30, 2001
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"III-Nitride Micro- and Nano-Structures and Devices"
Professor Hongxing Jiang , Kansas State
[Host: E. Kolomeisky and J. Poon]
Friday, March 23, 2001
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Quantum Entanglement as a Resource for Communication"
William Wootters , Williams College
[Host: Olivier Pfister]
Friday, March 9, 2001
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Using the World Wide Web for Physics Teaching and Learning: Exploring Where Pedagogy and Technology Meet"
Evelyn Patterson , U. S. Air Force Academy
[Host: Steve Thornton]
Friday, March 2, 2001
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Recent news from the vacuum? The Muon g-2 Experiment at Brookhaven"
B. Lee Roberts , Boston University
[Host: Blaine Norum]
Friday, February 23, 2001
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"First results from the Relativistic Heavy Ion Collider"
Jamie Nagle , Columbia University
[Host: Simonetta Liuti]
Friday, February 16, 2001
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Nanoscale ordering in soft materials near surfaces and interfaces"
Prof. Pulak Dutta , Northwestern Univ.
[Host: Joseph Poon]
Friday, February 9, 2001
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Neutron Spin Structure Function Measurements at Jefferson Lab"
Nilanga Liyanage , Jefferson Laboratory
[Host: Gordon Cates]
Thursday, February 8, 2001
4:00 PM
Physics Building, Room 204
Note special date.
Note special time.
Note special room.
Friday, January 19, 2001
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Ecological dynamics of multispecies communities"
Alan McKane , Department of Physics -University of Manchester, UK
[Host: Tim Newman]
Friday, December 8, 2000
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Quantum Confinement of Electrons and Phonons in Single Wall Carbon Nanotubes"
Prof. A T. Johnson, Jr. , Univ. of Pennsylvania
[Host: Joseph Poon]
Friday, November 10, 2000
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"The Musical Score, the Fundamental Theorem of Algebra, and the Measurement"
Rick Trebino , Georgia Tech
[Host: Louis Bloomfield]
Friday, November 3, 2000
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Women Becoming Mathematicians: The Doctoral Classes of 1940-1959"
Margaret Murray , Department of Mathematics, Virginia Tech
[Host: Simonetta Liuti]
Wednesday, November 1, 2000
4:00 PM
Physics Building, Room 204
Note special date.
Note special time.
Note special room.
"Quantum Entanglement and Quantum Teleportation"
Yanhua Shih , Univ. of Maryland Baltimore County
[Host: O. Pfister]
Friday, October 27, 2000
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
" Why do We Think Neutrinos Have Mass? And What's Next? "
Boris Kayser , National Science Foundation
[Host: P.Q. Hung]
Friday, October 20, 2000
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Friday, October 6, 2000
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
"Theory of de Broglie Waveguides"
Professor Marvin Girardeau , University of Arizona
[Host: Eugene Kolomeisky]
Monday, October 2, 2000
4:00 PM
Astronomy Building, Room 201
Note special date.
Note special time.
Note special room.
"Zeroing in on cosmological parameters"
Max Tegmark , University of Pennsylvania - Physics Dept.
[Host: T. X. Thuan]