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TT: Fachverband Tiefe Temperaturen
TT 50: Many-Body Localization
TT 50.4: Vortrag
Mittwoch, 18. März 2020, 18:45–19:00, HSZ 204
Dynamical quantum phase transitions and many-body localization in spin chains with quasiperiodic fields — •Leonardo Benini1, Piero Naldesi2, Rudolf Roemer1,3, and Tommaso Roscilde4 — 1University of Warwick, Coventry, U.K. — 2Université Grenoble-Alpes, LPMMC and CNRS, Grenoble, France — 3Université de Cergy-Pontoise, Institut d'Études Avancées, and LPT, Cergy-Pontoise, France — 4Université de Lyon, Ens de Lyon, Université Claude Bernard and CNRS, Lyon, France
We study dynamical properties of many-body localized systems through the lens of dynamical quantum phase transitions (DQPTs) theory. We explore the quench dynamics of a one-dimensional Heisenberg model with quasi-periodic on-site magnetic fields, investigating the emergence of singularities in the return rate of the Loschmidt echo both in the strong MBL regime and close to criticality. Quenching from an initially ordered Néel state, we show the appearance of a sequence of DQPTs deep in the MBL phase, periodically distributed along the real-time axis. We then establish a connection between the non-analytic behavior of the dynamical free energy and the oscillations of the spin imbalance. A second quench protocol, which investigates the non-equilibrium dynamics of the system initialized in its ground-state, provides additional insights on the emergence of DQPTs associated with the MBL phase. We develop an experimentally viable criterion to discern between the ergodic and the MBL phase exploiting non-analyticities of the Loschmidt free energy in the short-time dynamics.