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Many-Body Dephasing in a Trapped Ion Quantum Simulator

Date: 2019-08-21
Time: 10:00
Venue: M253
Speaker: Dr. Lingzhen Guo

Max Planck Institute for the Science of Light (MPL), Germany


After a quench in a quantum many-body system, expectation values tend to relax towards long-time averages. However, temporal fluctuations remain in the long-time limit, and it is crucial to study the suppression of these fluctuations with increasing system size. The particularly important case of nonintegrable models has been addressed so far only by numerics and conjectures based on analytical bounds. In this work, we are able to get analytical predictions for the temporal fluctuations in a nonintegrable model. We thus identify a dynamical regime of “many-body dephasing”, where the dephasing is not from thermalization but from the  lift of exponentially large degeneracies of transition energies. We also work together with the trapped-ion experimental group at Maryland University and present a recent (also first) experiment verifying the system size scaling predicted by many-body dephasing.

Brief CV of Dr. Lingzhen Guo:

Dr. Lingzhen Guo is a senior postdoc follow in Max Planck Institute for the Science of Light (MPL), Germany. In July 2013, He obtained a PhD degree from Beijing Normal University joined with Karlsruhe Institute of Technology (KIT) in Germany. From August 2013 to August 2014, he did postdoc research in the Institute of Theoretical Solid Physics at KIT. From September 2014 to August 2015, he continued his postdoc research in the Department of Microtechnology and Nanoscience (MC2) at Chalmers University of Technology, Sweden. From September 2015 to August 2017, he led a junior research group funded by Carl-Zeiss-Stiftung (200,000 €) at KIT. In January 2018, he joined the research group of Prof. Florian Marquardt at MPL and worked there till now. He works on quantum optics, quantum many-body physics and quantum information.