Bulletin of the American Physical Society
52nd Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 66, Number 6
Monday–Friday, May 31–June 4 2021; Virtual; Time Zone: Central Daylight Time, USA
Session Z08: Hot TopicsLive
|
Hide Abstracts |
Chair: Thad Walker, University of Wisconsin-Madison |
Friday, June 4, 2021 10:30AM - 11:00AM Live |
Z08.00001: Coherent Electron Dynamics Probed by XFELs Invited Speaker: Jonathan Marangos The question we address is the dynamical behaviour of quantum superpositions of electronic states in molecules; their formation, decoherence and coupling to the nuclear part of wavefunction. We concentrate upon electron hole superpositions created by a "fast" photoionization event that will result in the migration of charge through the formation of hole state superpositions (1h states) and superpositions of hole states and correlation satellites (1h-2h1p states). We employ an X-ray pump – X-ray probe methodology using both X-ray absorption spectroscopy (XAS) and X-ray electron emission spectroscopy (XPS) as a probe which circumvents the limits of previous methods. Earlier work to measure ultrafast electronic dynamics of such states has been centred around HHG spectroscopy and XUV pump – IR probe methods, but these are predominately confined to probing superpositions of outer valence hole states, do not give state and site specific resolved information and the optical fields used can significantly perturb the electron dynamics being studied. We will report the results of several recent experiments that capture the ultrafast dynamics of an electron hole in small molecular targets using few-femtosecond XFEL based pulses in a pump-probe measurement. An XAS measurement performed at LCLS studied isopropanol and identified charge migration dynamics in the form of a "breathing mode" in a superposition of inner valence states below the double ionization potential and so undergoing frustrated Auger-Meitner decay. Coherent hole dynamics was found in an XPS experiment at FLASH in glycine where the oscillatory character of an inner valence superposition with ~ 20 fs periodicity is captured. These results will be discussed, and a progress report will be given of measurements using attosecond XFEL pulses at LCLS ("Attosecond Campaign") investigating hole dynamics in the para-aminophenol molecule with extraordinary temporal resolution. |
Friday, June 4, 2021 11:00AM - 11:30AM Live |
Z08.00002: First Results from the Fermilab New Muon g-2 Experiment Invited Speaker: Timothy E Chupp Measurements of magnetic moment g-factors and a anomalies a=(g-2/2) of the electron and muon provide precision tests of the Standard Model and may reveal new physics. The lepton magnetic moment g-factor is larger than the Driac value g=2 due to interactions with the quantum vacuum. The largest contributions, a/2π~10-3 are from QED, and have been calculated to 10th order, while the strong and weak interactions contributions are ~10-7 and ~10-9 , respectively. Beyond-Standard Model Physics contributions mediated by heavy particles of mass scale mX are proportional to (ml/mx) 2 , which motivates study of g-2 for the muon. Over recent decades, aμ has been measured with increasing precision and theory has correspondingly improved, in particular in addressing hadronic contributions. Measurements at Brookhaven National Lab (BNL) for both positive and negative muons have precision 0.54 ppm, and the most recent theory compilation has precision 0.37 ppm. Tension of ~2.4 ppm or ~3.7 standard deviations motivated renewed experimental effort to move the magnet from BNL to Fermilab, develop an intense μ+ beam and the Fermilab Muon Campus, rebuild the experiment with state- of the art instrumentation, and support the analysis with simulations and a suite of new systematics studies. Analysis of the first year of data (Run 1) with statistics limited precision 0.46 ppm has recently been completed and is consistent with the previous result, increasing the tension to 4.2 standard deviations. In this talk I will describe the experiment and analysis in detail, present the result of Run 1, and discuss expectations for further measurements. |
Friday, June 4, 2021 11:30AM - 12:00PM Live |
Z08.00003: Distributed Quantum Sensing Empowered by Multipartite Entanglement and Machine Learning Invited Speaker: Zheshen Zhang Quantum information science (QIS) endows new capabilities for communications, computing, and sensing. Quantum entanglement is a unique resource that lies at the heart of QIS. In this talk, I will present our recent work of harnessing entanglement to interconnect a network of sensors to achieve measurement performance beyond the reach of classical sensor networks. I will discuss how state-of-the-art machine-learning tools have been utilized to train an entangled sensor network to undertake data-processing tasks. Our work would create new opportunities for positioning, navigation, and imaging. |
Friday, June 4, 2021 12:00PM - 12:30PM Live |
Z08.00004: Quantum Register of Fermion Pairs Invited Speaker: Martin W Zwierlein Fermions are the building blocks of matter, forming atoms and nuclei, complex materials and neutron stars. Our understanding of many-fermion systems is however limited, as classical computers are often insufficient to handle the intricate interplay of the Pauli principle with strong interactions. Quantum simulators based on ultracold fermionic atoms instead directly realize paradigmatic Fermi systems, albeit in "analog" fashion, without coherent control of individual fermions. Digital qubit-based quantum computation of fermion models, on the other hand, faces significant challenges in implementing fermionic anti-symmetrization, calling for an architecture that natively employs fermions as the fundamental unit. In this talk we demonstrate a robust quantum register composed of hundreds of fermionic atom pairs trapped in an optical lattice. With each fermion pair forming a spin-singlet, the qubit is realized as a set of near-degenerate, symmetry-protected two-particle wavefunctions describing common and relative motion. Degeneracy is lifted by the atomic recoil energy, only dependent on mass and lattice wavelength, thereby rendering two-fermion motional qubits insensitive against noise of the confining potential. We observe quantum coherence beyond ten seconds. Universal control is provided by modulating interactions between the atoms. Via state-dependent, coherent conversion of free atom pairs into tightly bound molecules, we tune the speed of motional entanglement over three orders of magnitude, yielding $10^4$ Ramsey oscillations within the coherence time. For site-resolved motional state readout, fermion pairs are coherently split into a double well, creating entangled Bell pairs. The methods presented here open the door towards fully programmable quantum simulation and digital quantum computation based on fermions. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700