Joint ICTP/SISSA SP Seminar @ICTP Stasi Room: R.MOESSNER Tuesday 18 April at 11:00

[Condensed Matter Section]

Joint ICTP/SISSA Statistical Physics Seminar

Tuesday, 18 April at 11:00 a.m.
Luigi Stasi Seminar Room, first floor, ICTP Leonardo building

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Speaker: Roderich MOESSNER (MPI Komplexer Systeme, Dresden, Germany)


Title:
Thermodynamics and Order Beyond Equilibrium - The Physics of Periodically
Driven Quantum Systems

Abstract:

The field of thermodynamics is one of the crown jewels of classical 
physics. However, only comparatively recently, due to the advent 
ofexperiments in cold atomic systems with long coherence times, has 
ourdetailed understanding of its connection to quantum statistical 
mechanics seen remarkable progress.

Extending these ideas and concepts to the non-equilibrium setting is a 
challenging topic, in itself of perennial interest. Here, we study 
perhaps the simplest non-equilibrium class of quantum problems, namely 
Floquet systems, i.e. systems whose Hamiltonians depend on time 
periodically, $H(t + T) = H(t)$. For these, there is no energy 
conservation, and hence not even a natural concept of temperature.

We find that it is nonetheless possible to identify several 
fundamentally distinct thermodynamic ensembles.  We also ask if there 
exists a sharp notion of a phase in such driven, interacting quantum
systems. Disorder turns out to play a crucial role, enabling the 
existence of states which are straightforward analogues of equilibrium 
states with broken symmetries and topological order, while 
others--genuinely new to the Floquet problem--are characterized by a 
combination of order and non-trivial periodic dynamics.

This work was done in collaboration with Arnab Das, Vedika Khemani, 
Achilleas Lazarides and Shivaji Sondhi.

References: Phys. Rev. Lett. 112, 150401 (2014); Phys. Rev. E 90 , 
012110 (2014); Phys. Rev. Lett. 115, 030402 (2015); Phys. Rev. Lett. 
116, 250401 (2016)