Berlin 2018 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 40: Dual-Method Approaches to Quantum Many-Body Systems II

TT 40.8: Vortrag

Dienstag, 13. März 2018, 12:00–12:15, H 3010

Geometry of driven-dissipative phase transitions — •Mikhail Pletyukhov¹, Dmitry Krimer², and Maarten Wegewijs^1,3 — ¹Institute for Theory of Statistical Physics, RWTH Aachen University, Germany — ²Institute for Theoretical Physics, TU Wien, Austria — ³Peter Grünberg Institute, Forschungszentrum Jülich, Germany

Recent progress in the study of driven dissipative phase transitions in open quantum systems has raised the question how hysteretic phenomena in many-body systems can be appropriately understood on a quantum level, going beyond the common semiclassical mean-field description. In this talk we explain how hysteresis generically arises when accounting for a typical measurement time. We directly tie this to the eigenmodes of a nonunitary Lindblad dynamics of which a metastable state is composed. The metastable state attained on this given measurement timescale depends on the whole experimental procedure (a sequence of all preceding runs). This dependence must be accounted for at every subsequent experimental run. We show that different branches in the parametric dependence of observables then emerge naturally from the linear quantum master equation. Interestingly, these metastable states can be understood in terms of their path-dependent amplitudes in the Liouvillian-eigenmode expansion. Such amplitudes are familiar from pumping problems in quantum transport that can be related to geometric "phases" of the Landsberg type.