Abstract
One of the outstanding problems in nonequilibrium physics is to precisely understand when and how physically relevant observables in many-body systems equilibrate under unitary time evolution. General equilibration results show that equilibration is generic provided that the initial state has overlap with sufficiently many energy levels. But results not referring to typicality which show that natural initial states actually fulfill this condition are lacking. In this work, we present stringent results for equilibration for systems in which Rényi entanglement entropies in energy eigenstates with finite energy density are extensive for at least some, not necessarily connected, subsystems. Our results reverse the logic of common arguments, in that we derive equilibration from a weak condition akin to the eigenstate thermalization hypothesis, which is usually attributed to thermalization in systems that are assumed to equilibrate in the first place. We put the findings into the context of studies of many-body localization and many-body scars.
- Received 18 March 2019
- Revised 4 July 2019
DOI:https://doi.org/10.1103/PhysRevLett.123.200604
© 2019 American Physical Society
Physics Subject Headings (PhySH)
Viewpoint
Equilibration in Quantum Systems
Published 13 November 2019
Two research groups show that specific contributions to entropy may be the key to understanding how and when quantum systems equilibrate.
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