MATHEMATICAL PHYSICS WEBINAR
RUTGERS UNIVERSITY
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David A. Huse – Princeton University
Wednesday, January 8th , 10:45AM EST
Thermalization of Quantum Many-Body Folquet Systems
This talk will explore some aspects of how generic local quantum many-body systems go to thermal equilibrium as closed systems under their own unitary dynamics. Some of the essence of this is captured by Floquet systems of qubits (spin ½’s) with no conservation laws other than the unitarity of the operator that produces the discrete-time dynamics. Such systems approach thermal equilibrium exponentially with time, but the spectrum of the unitary operator producing the dynamics does not show any gap setting the time scale of this exponential approach to equilibrium. This time scale is instead set by the dynamics of operator spreading. An explicit gap, that sets the rate of equilibration, in the super-operator that generates the dynamics can be produced by: adding weak local dissipation, taking the limit of a large system, and then taking the limit of zero dissipation. The closed system is a dissipative bath for itself, and this order of limits makes this bath explicitly dissipative instead of unitary.