SP Seminar @ICTP Luigi Stasi Seminar Room Tuesday 17 April 11 am A. WINTER

[CM Section]

Joint ICTP/SISSA Statistical Physics Seminar

Tuesday 17 April at 11:00 a.m.
Luigi Stasi Seminar Room, first floor, Leonardo Building

Andreas J. WINTER (University of Barcelona)

"Microcanonical and resource-theoretic derivations of the grand
canonical thermal state of a system with non-commuting charges"

Abstract: The grand canonical ensemble lies at the core of
quantum and classical statistical mechanics. A small system
thermalizes to this ensemble while exchanging heat and particles
with a bath. A quantum system may exchange quantities represented
by operators that fail to commute. Whether such a system
thermalizes and what form the thermal state has are questions
about truly quantum thermodynamics. Here we investigate this
thermal state from three perspectives. First, we introduce an
approximate microcanonical ensemble. If this ensemble
characterizes the system-and-bath composite, tracing out
the bath yields the system's thermal state. This state is
expected to be the equilibrium point, we argue, of typical
dynamics. Finally, we define a resource-theory model for
thermodynamic exchanges of noncommuting observables. Complete
passivity
  --
the inability to extract work from equilibrium
states-- implies the thermal state's form, too. Our work opens
new avenues into equilibrium in the presence of quantum
noncommutation.
[Based on 1512.01189 with N. Yunger Halpern, P. Faist an