Thouless and Relaxation Time Scales in Many-Body Quantum Systems

Lea F. Santos, Professor of Physics, Yeshiva University, New York

A major open question in studies of nonequilibrium quantum dynamics is the identification of the time scales involved in the relaxation process of isolated quantum systems that have many interacting particles. Using experimental observables and a realistic disordered many-body quantum model, we unveil three different time scales: a very short time that characterizes the early fast decay of the initial state, and two much longer times that increase exponentially with system size. These are the Thouless time and the relaxation time. The Thouless time refers to the point beyond which the dynamics acquire universal features, and relaxation happens when the evolution reaches a stationary state. We show that in chaotic systems, the Thouless time is much smaller than the relaxation time, while for systems approaching a many-body localized phase, they merge together.  Our results are compared with those for random matrices, which corroborates their generality.

 

Dr. Lea F. Santos is a Professor of Physics with a Ph.D. in theoretical physics from the University of São Paulo. Postdoctoral experience included work in random matrix theory at Yale, and developing new dynamical decoupling techniques at Dartmouth College. She is a member of the APS, IOP, IAMP, AAPT, Anacapa Society, and Committee of the Concerned Scientist.

Teaching and Research Interests:
Research interests include quantum transport, thermalization of isolated and open quantum systems, localization, metal-insulator transition, quantum chaos, two-body random ensembles, spin systems, dynamics of fermionic and bosonic systems with correlated and uncorrelated on-site disorder, quantum control, dynamical decoupling methods, decoherence, quantum-classical transition, measurement problem, and foundations of quantum mechanics.