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SUMMARY:Thermodynamics beyond equilibrium -- the physics of periodically d
 riven quantum systems&quot\; - Prof. Dr. Roderich Moessner\, Max Planck In
 stitute for the Physics of Complex Systems\, Dresden
DTSTART:20151111T160000Z
DTEND:20151111T170000Z
UID:TALK61671@talks.cam.ac.uk
CONTACT:Leona Hope-Coles
DESCRIPTION:The field of thermodynamics is one of the crown jewels of clas
 sical physics. Extending its ideas and concepts to the non-equilibrium set
 ting is a challenging topic of perennial interest. Here\, we study perhaps
  the simplest non-equilibrium class of quantum problems\, namely Floquet s
 ystems\, 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 definition of temperature. We find that it is nonetheless p
 ossible to identify three fundamentally distinct thermodynamic ensembles. 
 We also ask if there exists a sharp notion of a phase in such driven\, int
 eracting quantum systems. Disorder turns out to play a crucial role\, enab
 ling the existence of states which are straightforward analogues of equili
 brium states with broken symmetries and topological order\, while others -
 - genuinely new to the Floquet problem -- are characterized by a combinati
 on of order and non-trivial periodic dynamics. \n\nThis work was done in c
 ollaboration with Arnab Das\, Vedika Khemani\, Achilleas Lazarides and Shi
 vaji Sondhi: Phys. Rev. Lett. 112\, 150401 (2014)\; Phys. Rev. E 90\, 0121
 10 (2014)\; Phys. Rev. Lett. 115\, 030402 (2015)\; arXiv:1508.03344. \n
LOCATION:Pippard Lecture Theatre\, Cavendish Laboratory
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