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SUMMARY:Thermalization vs localization in a solvable circuit model - Anush
 ya Chandran\, Perimeter Institute
DTSTART:20150814T130000Z
DTEND:20150814T140000Z
UID:TALK60358@talks.cam.ac.uk
CONTACT:Gareth Conduit
DESCRIPTION:Isolated quantum dynamics need not lead to local thermal equil
 ibrium in the presence of sufficient quenched disorder. This many-body loc
 alized phase is not described by equilibrium statistical mechanics. At low
 er disorder however\, the system transitions into a conventional thermal p
 hase. Very little is known about the dynamical transition between the two 
 phases\, especially in spatial dimensions greater than one. In this talk\,
  I will introduce a simple circuit model for the localization-delocalizati
 on dynamical transition in the absence of global symmetries. The tractabil
 ity of the model arises from the restriction of the gates in the circuit t
 o Clifford gates. In d=1\, the resulting dynamics are always many-body loc
 alized with a complete set of strictly local integrals of motion. In d>=2\
 , the system realizes both localized and delocalized phases separated by a
  continuous transition in which ergodic puddles percolate. I will argue th
 at the phases are stable to small deformations of the circuits\, estimate 
 the resulting phase boundary and conjecture bounds on the critical exponen
 ts for the generic transition. The Clifford circuit model is a distinct tr
 actable limit from that of free fermions and is a toy dynamical system to 
 test thermalization in. 
LOCATION:TCM Seminar Room\, Cavendish Laboratory
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