"Science at Jefferson Laboratory: The amazing world of quarks and gluons"David Dean , Jefferson Laboratory [Host: Simonetta Liuti]
ABSTRACT:
Nuclei make up 99% of the mass in the visible universe, and all but the lightest nuclei are produced in cataclysmic stellar events such as supernova explosions and neutron star mergers. Every proton (and neutron) within all nuclei is governed by QCD, the theory of quarks, gluons, and their interactions. Understanding the amazing world inside a proton requires tremendous technical capabilities embodied in large accelerator facilities and advanced detector technology, as found at the world-class facilities of Jefferson Laboratory. These capabilities enable us to understand how QCD supports the dynamical generation of bound states with a rich variety as seen from data. Interestingly, the more closely one peers into a proton (with higher-energy electrons), the more complex the emergent phenomena one measures. Tying these measurements to theory often requires models informed by LQCD calculations. Furthermore, JLab’s experimental capabilities, using parity violation, have recently enabled a precise measurement of the thickness of the neutron skin in Pb which has implications in the astrophysics associated with neutron-star mergers. This interplay is but one demonstration of how the world of the small, even at the proton level, affects the most violent of collisions in the universe. VIDEO:
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Colloquium Friday, January 20, 2023 3:30 PM Clark Hall, Room 108 Note special room. About David Dean: David Dean is the Deputy Director for Science and Chief Research Officer of Thomas Jefferson National Accelerator Facility (JLab). See further details at https://www.jlab.org/news/releases/david-j-dean-appointed-jefferson-lab-deputy-director-science https://web.phys.virginia.edu/Private/Covid-19/colloquium.asp |
"Unraveling the origin of neutrino masses"Julian Heeck , UVA-High Energy Physics [Host: Despina Louca]
ABSTRACT:
Non-zero neutrino masses provide the strongest evidence for physics beyond the Standard Model of particle physics. Large neutrino detectors and cosmological observations provide more and more information about neutrino masses and mixing angles, and might soon converge toward a self-consistent description with precisely measured parameters. The origin of neutrino masses remains mysterious, however, with a seemingly unlimited number of possible models flooding the literature. I will discuss ways to potentially distinguish certain classes of models and how to render a neutrino-mass theory predictive by connecting it to other anomalous observables such as the muon’s magnetic moment or CDF’s W-boson mass. VIDEO:
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Colloquium Friday, January 27, 2023 3:30 PM Clark Hall, Room 108 Note special room. https://web.phys.virginia.edu/Private/Covid-19/colloquium.asp |
"Machine learning concepts for inverse materials design"Andrea Liu , University of Pennsylvania [Host: Marija Vucelja]
ABSTRACT:
In order for artificial neural networks to learn a task, one must solve an inverse design problem. What are all the node weights for the network that will give the desired output? The method by which this problem is solved by computer scientists can be harnessed to solve inverse design problems in soft matter. I will discuss how we have used such approaches to design mechanical and flow networks that can perform functions inspired by biology. I will also show how we can exploit physics to go beyond artificial neural networks by using local rules rather than global gradient descent approaches to learn in a distributed way. |
Colloquium Friday, February 3, 2023 3:30 PM Clark Hall, Room 108 Note special room. https://web.phys.virginia.edu/Private/Covid-19/colloquium.asp |
"Uncovering Chirality of Skyrmions in Polycrystalline B20 FeGe on Si"Kayla Nguyen [Host: Despina Louca]
ABSTRACT:
Understanding chirality, the intrinsic handedness of a system, is important for future technologies using quantum magnetic materials. Of particular interest are magnetic skyrmions which are chiral and topologically protected, meaning that their spin textures can act as barriers from deformation in crystalline grains. However, most electron microscopy studies use Lorentz TEM or holography to investigate chirality in skyrmions in nearly perfect single crystals because Fresnel effects may cause signals from grain structures to be mistaken as magnetism when the two are comparable in size. In this work, we probe nanomagnetism of topological magnetic textures in sputtered thin film of B20 FeGe on Si to study the relationship between magnetic and crystal chirality. Using 4D-STEM, we find that the vorticity and helicity of these magnetic topological phases are coupled to the crystal chirality. Furthermore, our work shows that signals from magnetism can be disentangled from crystalline effects for sub-micron grains, enabling a new way to investigate topological magnetism in the presence of small polycrystalline grains. This methodology is important for spintronics and low-power magnetic memory technologies that rely on scalable techniques for large scale manufacturing of real devices. |
Colloquium Friday, February 10, 2023 3:30 PM Clark Hall, Room 108 Note special room. https://web.phys.virginia.edu/Private/Covid-19/colloquium.asp |
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Colloquium Friday, February 17, 2023 3:30 PM Clark Hall, Room 108 Note special room. https://web.phys.virginia.edu/Private/Covid-19/colloquium.asp |
ABSTRACT:
Our solar system is embedded in the Local Bubble, an expanding, 1,000-light-year-wide cavity in the interstellar medium (ISM). The Bubble was created ~14 million years ago by a chain of supernova explosions that drove out most of the diffuse dust and gas in the nearby ISM. Recent work mapping the 3D shape and dynamics of the Local Bubble has revealed that nearly all recent star formation within |
Colloquium Friday, February 24, 2023 3:30 PM Clark Hall, Room 108 Note special room. |
"The Search for Hidden Structures in the Temple of Kukulcan at Chichen Itza Using Cosmic-Ray Muons"Sydney Roberts , UVA [Host: Stefan Baessler]
ABSTRACT:
Using muon tomography, the Non-invasive Archaeometry Using Muons (NAUM) Project will image the interiors of ancient Maya temples in Chichén Itzá, Mexico to uncover their unknown internal structures. |
Colloquium Friday, February 24, 2023 4:00 PM Clark Hall, Room 108 Note special time. Note special room. https://web.phys.virginia.edu/Private/Covid-19/colloquium.asp |
ABSTRACT:
Dark matter is believed to make up most of the matter in our Universe, but its particle origin remains a mystery. A favorite candidate is the so-called Weakly Interacting Massive Particle (WIMP), but a diverse set of experiments are rapidly closing the available parameter space for WIMPs. I will show that small changes to the assumptions about how dark matter was produced in the early Universe lead to very different dark matter masses and interaction strengths. I will chart ``phase diagrams” for the production of dark matter with a thermal or non-thermal origin. I will explain how different phases of dark matter production map onto different experimental prospects. |
Colloquium Friday, March 3, 2023 3:30 PM Clark Hall, Room 108 Note special room. https://web.phys.virginia.edu/Private/Covid-19/colloquium.asp |
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Colloquium Friday, March 17, 2023 3:30 PM Clark Hall, Room 108 Note special room. https://web.phys.virginia.edu/Private/Covid-19/colloquium.asp |
"Tapping into quantumness of condensed matter with color centers"Prof. Yaroslav Tserkovnyak , UCLA [Host: Prof. Israel Klich]
ABSTRACT:
Combining low-dimensional correlated condensed matter systems with judiciously placed and optically accessible quantum impurities is a fruitful enterprise for (1) diverse sensing modalities of fundamental equilibrium and transport properties in a variety of systems, (2) designing and building up quantum-entangled dynamics of the quantum bit ensembles, and (3) using such dynamics to imprint measurable quantum correlations back onto the condensed matter systems and devices. This interplay between macroscopically controlled solid-state heterostructures and intricate highly-correlated quantum dynamics of atomistic quantum degrees of freedom opens up a rich and versatile playground for fusing ideas from quantum optics, quantum transport, and quantum material sensing and engineering. I will summarize our current ideas, focusing on the overarching symmetry and nonequilibrium thermodynamics based reasoning. |
Colloquium Friday, March 24, 2023 3:00 PM Clark Hall, Room 108 Note special time. Note special room. https://web.phys.virginia.edu/Private/Covid-19/colloquium.asp |
"Scaling down the laws of thermodynamics"Christopher Jarzynski , University of Maryland [Host: Marija Vucelja]
ABSTRACT:
Thermodynamics provides a robust conceptual framework and set of laws that govern the exchange of energy and matter. Although these laws were originally articulated for macroscopic objects, nanoscale systems also exhibit “thermodynamic-like” behavior – for instance, biomolecular motors convert chemical fuel into mechanical work, and single molecules exhibit hysteresis when manipulated using optical tweezers. To what extent can the laws of thermodynamics be scaled down to apply to individual microscopic systems, and what new features emerge at the nanoscale? I will describe some of the challenges and recent progress – both theoretical and experimental – associated with addressing these questions. Along the way, my talk will touch on non-equilibrium fluctuations, “violations” of the second law, the thermodynamic arrow of time, nanoscale feedback control, strong system-environment coupling, and quantum thermodynamics. |
Colloquium Friday, March 31, 2023 3:30 PM Clark Hall, Room 108 Note special room. https://web.phys.virginia.edu/Private/Covid-19/colloquium.asp |
"Flatland quantum simulation and visualization with atomic resolution"Yulia Maximenko , NIST Gaithersburg [Host: Despina Louca]
ABSTRACT:
Quantum computing and simulation promise to revolutionize fundamental physics, technology, and quantum chemistry. Simulating quantum systems using analog platforms was first proposed in the 1980s, but recent technological advances have brought this idea to new heights. Trapped atoms and ions, superconducting circuits, and advanced solid-state platforms have achieved an unprecedented level of quantum control and are able to model increasingly complex Hamiltonians. Quantum simulation in 2D solid platforms has proved to be incredibly versatile, while also being compatible with the existing semiconductor technology. In this colloquium, I will showcase the exciting recent developments in the field of 2D quantum simulators, highlighting twisted moiré systems and atomic manipulation. Scanning tunneling microscopy (STM) has proved crucial for the progress of this field. My focus will be on revealing the topological and strongly correlated physics in twisted layered graphene and on the surprising insights gained through the use of STM. Through high-resolution magnetic field scanning tunneling spectroscopy, we have demonstrated the importance of the fine details of quantum geometry in these novel 2D platforms. Specifically, I will report on the discovery of an emergent anomalously large orbital magnetic susceptibility in twisted double bilayer graphene, along with the orbital magnetic moment. I will also discuss the exciting future potential in the field of quantum materials, combining STM, epitaxial growth, and stacked 2D devices. |
Colloquium Wednesday, April 5, 2023 11:00 AM Ridley Hall, Room G006 Note special date. Note special time. Note special room. https://web.phys.virginia.edu/Private/Covid-19/colloquium.asp |
"When nature entangles millions of particles: from quantum materials to black holes"Subir Sachdev , Harvard [Host: David Nichols]
ABSTRACT:
Entanglement is the strangest feature of quantum theory, often dubbed ''spooky action at a distance’’. Quantum entanglement can occur on a macroscopic scale with trillions of electrons, leading to "strange metals" and novel superconductors which can conduct electricity without resistance even at relatively high temperatures. Remarkably, related entanglement structures arise across the horizon of a black hole, and give rise to Hawking’s quantum paradox. This lecture will be designed to introduce these forefront topics in current physics research to a general audience. |
Colloquium Thursday, April 6, 2023 7:00 PM Gilmer Hall, Room 301 Note special date. Note special time. Note special room. Hoxton Lecture |
"Interfacing Quantum Information and Quantum Sensing "Charlotte Boettcher , Yale [Host: Despina Louca]
ABSTRACT:
Quantum information is a rapidly growing field that continues to develop and explore a variety of platforms to realize scalable quantum devices. Progress in qubit technology is driven by continued advancement in materials research, which informs fundamental issues such as the underlying mechanisms limiting qubit coherence times. Further, quantum materials including superconductors, magnets, insulators, and topological materials all offer unique properties that can be implemented into quantum circuits to realize new functionalities. In this way, the fundamental physics of quantum materials is intertwined with the development of next-generation quantum devices. |
Colloquium Friday, April 7, 2023 3:30 PM Clark Hall, Room 108 Note special room. https://web.phys.virginia.edu/Private/Covid-19/colloquium.asp |
ABSTRACT:
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Colloquium Friday, April 14, 2023 3:30 PM Clark Hall, Room 108 Note special room. https://web.phys.virginia.edu/Private/Covid-19/colloquium.asp |
"Dark Matter in the Universe"Professor Katherine Freese , University of Texas, Austin [Host: Prof. PQ Hung]
ABSTRACT:
The nature of the dark matter in the Universe is among the longest and most important outstanding problems in all of modern physics. The ordinary atoms that make up the known universe, from our bodies and the air we breathe to the planets and stars, constitute only 5% of all matter and energy in the cosmos. The remaining 95% is made up of a recipe of 25% dark matter and 70% dark energy, both nonluminous components whose nature remains a mystery. I’ll begin by discussing the evidence that dark matter is the bulk of the mass in the Universe, and then turn to the hunt to understand its nature. Leading candidates are fundamental particles including Weakly Interacting Massive Particles (WIMPs), axions, sterile neutrinos, as well as primordial black holes. I will discuss multiple experimental searches: at CERN in Geneva; in underground laboratories; with space telescopes; with gravitational wave detectors; and even with DNA. I’ll tell you about our novel idea of Dark Stars, early stars powered by dark matter heating, and the possibility that the James Webb Space Telescope could find them. At the end of the talk, I'll turn to dark energy and its effect on the future of the Universe. |
Colloquium Friday, April 21, 2023 3:30 PM Clark Hall, Room 108 Note special room. https://web.phys.virginia.edu/Private/Covid-19/colloquium.asp |
ABSTRACT:
TBA |
Colloquium Friday, April 28, 2023 3:30 PM Clark Hall, Room 108 Note special room. https://web.phys.virginia.edu/Private/Covid-19/colloquium.asp |
ABSTRACT:
TBA |
Colloquium Friday, May 5, 2023 3:30 PM Clark Hall, Room 108 Note special room. https://web.phys.virginia.edu/Private/Covid-19/colloquium.asp |
To add a speaker, send an email to dn2ep@Virginia.EDU Include the seminar type (e.g. Colloquia), date, name of the speaker, title of talk, and an abstract (if available). [Please send a copy of the email to phys-speakers@Virginia.EDU.]