%0 Journal Article
%A Novotny, M. A.
%A Jin, F.
%A Yuan, S.
%A Miyashita, S.
%A De Raedt, H.
%A Michielsen, K.
%T Quantum decoherence and thermalization at finite temperature within the canonical-thermal-state ensemble
%J Physical review / A
%V 93
%N 3
%@ 2469-9926
%C College Park, Md.
%I APS
%M FZJ-2016-01906
%P 032110
%D 2016
%X We study measures of decoherence and thermalization of a quantum system S in the presence of a quantum environment (bath) E. The entirety S+E is prepared in a canonical-thermal state at a finite temperature; that is, the entirety is in a steady state. Both our numerical results and theoretical predictions show that measures of the decoherence and the thermalization of S are generally finite, even in the thermodynamic limit, when the entirety S+E is at finite temperature. Notably, applying perturbation theory with respect to the system-environment coupling strength, we find that under common Hamiltonian symmetries, up to first order in the coupling strength it is sufficient to consider S uncoupled from E, but entangled with E, to predict decoherence and thermalization measures of S. This decoupling allows closed-form expressions for perturbative expansions for the measures of decoherence and thermalization in terms of the free energies of S and of E. Large-scale numerical results for both coupled and uncoupled entireties with up to 40 quantum spins support these findings.
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:000371724100003
%R 10.1103/PhysRevA.93.032110
%U https://juser.fz-juelich.de/record/283596