Group Seminar at LMU: Prethermal Matter in Long-range Interacting Systems

January 09, 2020

Francisco Machado, UC Berkeley
LMU München, Schellingstr. 4
Seminar room H 107
Thursday 01/09, 09:15am


Recent developments in atomic, molecular and optical systems have enabled unprecedented access to novel out-of-equilibrium phenomena---even in strongly interacting many-body systems. Such techniques have led to an explosion of excitement in this field, with particular attention being given to periodically driven systems. In such systems, the discrete time translation symmetry of the evolution leads to entirely new phases of matter, but also to one major hurdle in the study of out-of-equilibrium phenomena: the heating problem. More specifically, a generic strongly interacting driven system will continuously absorb energy from the drive until it approaches the infinite temperature state at late times, destroying any interesting out-of-equilibrium behavior.
In this talk, I will discuss an approach to overcome this hurdle: prethermalization. By considering high frequency driven systems, the heating rate from the drive becomes exponentially small, enabling a parametrically large time scale for observing out-of-equilibrium phases of matter. I will discuss our recent work in extending this approach to long-range interacting systems---of particular interest to many experimental platforms amenable to quantum simulation. I will focus on describing how long-range interactions affect the dynamics within the prethermal regime and how an emergent symmetry can arise (protected by the time translation symmetry of the drive). Leveraging this emergent symmetry, the system can host novel phases of matter within the prethermal regime that have no static analogue. I will present an example of such a phase, the one dimensional prethermal time crystal. Finally, time permitting, I will discuss how these results extend to classical dynamics. I will focus on the dynamics within the classical prethermal regime, and then show how, as in the quantum case, classical systems can host novel prethermal phases of matter.

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