Atomic Physics Seminars
Professor Xu Yi , University of Virginia - ECE and Physics
[Host: Peter Schauss]
Scalability is the central challenge in universal quantum computing, which has long established revolutionary premises, such as exponential speedup of difficult to near-impossible computations. A promising platform towards scalable quantum computing is the quantum optical frequency comb, which leverages optical frequency multiplexing and produces thousands of unconditional EPR entanglement in a single oscillator. In this talk, I will present our recent work to miniaturize the quantum optical frequency comb to a photonic chip for the first time. Our work brings the power of microfabrication to quantum optical applications, and could enable low cost mass-production, which promises additional scalability. I will also briefly discuss the roadmap and the challenges towards scalable quantum computing with integrated photonic frequency combs.
Meeting ID: 937 8726 3270 Passcode: 5i728c
Monday, November 16, 2020
Online, Room via Zoom
Note special room.
Julio Barreiro , University of California San Diego
[Host: Peter Schauss]
Systems of ultracold particles with strong interactions and correlations lie at the heart of many areas of the physical sciences, from atomic, molecular, optical, and condensed-matter physics to quantum chemistry. In condensed matter, strong interactions determine the formation of topological phases giving materials unexpected physical properties that could revolutionize technology through robustness to noise and disorder. In this talk I will report on our work towards the realization of a fractional Chern insulator state using our experimental apparatus producing degenerate Fermi gases of strontium. Our simulation of the topological insulating state will follow an optical flux approach, which engineers the lattice in reciprocal space through polychromatic beams driving a manifold of stimulated Raman transitions, and will benefit from ultracold strontium's low temperatures and reduced heating by spontaneous emission.
On the other hand, systems of ultracold particles without interactions reveal matter-wave properties with enhanced interferometric sensitivity. I will discuss our ongoing efforts to trap ultracold strontium atoms on the evanescent fields of nanophotonic waveguides and nanotapered optical fibers. The existence of magic blue and red detuned wavelengths lead to a trapping volume that can be continuously and robustly loaded with ultracold strontium via a transparency beam. Fundamental studies of Casimir and Casimir-Polder physics as well as several applications, such as field sensors and matter-wave interferometers, will be possible with these platforms.
Professor Varun Makhija , University of Mary Washington
[Host: Bob Jones]
The development of ultrashort, broadband light pulses in the vacuum ultraviolet enables resonant excitation and probing of the dynamics of isolated molecules. Since the total angular momentum of an isolated system is conserved, broadband excitation necessarily leads to a coherent wavepacket of angular momentum states. Coherences between states of different angular momentum physically manifest as a time varying alignment or orientation of the molecular axis, as well as a much faster variation in the alignment or orientation of the electronic probability distribution, which is synchronized with electronic dynamics occurring in the molecular frame. I will present a direct and selective measurement of this time varying electronic anisotropy, and the potential application of ultrafast scattering probes to this end. I will also briefly discuss the application of purely rotational coherences in the electronic ground state to extract molecular frame information, particularly in the context of photoionization.
Thursday, January 30, 2020
Physics Building, Room 204
Note special date.
Note special time.
Avi Pe'er , Bar-Ilan University
[Host: Olivier Pfister]
The sensitivity of classical Raman spectroscopy methods, such as coherent anti-stokes Raman spectroscopy (CARS) or stimulated Raman spectroscopy (SRS), is ultimately limited by shot-noise from the stimulating fields. I will present a squeezing-enhanced version of Raman spectroscopy that overcomes the shot-noise limit of sensitivity with enhancement of the Raman signal and inherent background suppression, while remaining fully compatible with standard Raman spectroscopy methods. By incorporating the Raman sample between two phase-sensitive parametric amplifiers that squeeze the light along orthogonal quadrature axes, the typical intensity measurement of the Raman response is converted into a quantum-limited, super-sensitive estimation of phase. The resonant Raman response in the sample induces a phase shift to signal-idler frequency-pairs within the fingerprint spectrum of the molecule, resulting in amplification of the resonant Raman signal by the squeezing factor of the parametric amplifiers, whereas the non-resonant background is annihilated by destructive interference. Seeding the interferometer with classical coherent light stimulates the Raman signal further without increasing the background, effectively forming squeezing-enhanced versions of CARS and SRS, where the quantum enhancement is achieved on top of the classical stimulation.
 Yoad Michael, Leon Bello, Michael Rosenbluh and Avi Pe’er, “Squeezing-enhanced Raman Spectroscopy”, npj – Quantum Information 5, 81 (2019) .
 Y. Shaked, Y. Michael, R. Vered, M. Rosenbluh and A. Pe’er, “Lifting the Bandwidth Limit of Optical Homodyne Measurement,” Nature Communications 9, 609 (2018).
To add a speaker, send an email to ps5nw@Virginia.EDU Include the seminar type (e.g. Atomic Physics Seminars), 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.]