Authors: Markus P Müller Emily Adlam Lluís Masanes Nathan Wiebe
Publish Date: 2015/09/10
Volume: 340, Issue: 2, Pages: 499-561
Abstract
It has previously been suggested that small subsystems of closed quantum systems thermalize under some assumptions however this has been rigorously shown so far only for systems with very weak interaction between subsystems In this work we give rigorous analytic results on thermalization for translationinvariant quantum lattice systems with finiterange interaction of arbitrary strength in all cases where there is a unique equilibrium state at the corresponding temperature We clarify the physical picture by showing that subsystems relax towards the reduction of the global Gibbs state not the local Gibbs state if the initial state has close to maximal population entropy and certain nondegeneracy conditions on the spectrumare satisfiedMoreoverwe showthat almost all pure states with support on a small energy window are locally thermal in the sense of canonical typicality We derive our results from a statement on equivalence of ensembles generalizing earlier results by Lima and give numerical and analytic finite size bounds relating the Ising model to the finite de Finetti theorem Furthermore we prove that global energy eigenstates are locally close to diagonal in the local energy eigenbasis which constitutes a part of the eigenstate thermalization hypothesis that is valid regardless of the integrability of the model
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