Regensburg 2016 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 4: Dynamics in many-body systems: Equilibriation and localization (joint session DY/TT)

DY 4.5: Vortrag

Montag, 7. März 2016, 10:30–10:45, H47

The eigenstate thermalization hypothesis as driving force behind initial state independent equilibration in closed quantum systems — •Christian Bartsch and Jochen Gemmer — Fachbereich Physik, Universität Osnabrück, Barbarastraße 7, D-49069 Osnabrück

We analyze the long time behavior of non-equilibrium expectation value dynamics for finite closed quantum systems considering very general Hamiltonians and observables. For a certain class of generic, i.e., experimentally realistic, initial states we analytically find that the long time expectation value depends on the concrete initial state and in general deviates from the expected average equilibrium value unless the eigenstate thermalization hypothesis (ETH) is fulfilled. We call this behavior stick effect. The initial states may be prepared by exposition of the system to a super bath in combination with an additional potential which depends on the regarded observable, thus the system is explicitly out of equilibrium and the initial state is correlated with both the Hamiltonian and the observable, i.e., the situation is not covered by established investigations involving typicality in terms of the Haar measure. The results suggest that the ETH may serve not only as a sufficient but also as a necessary condition for initial state independent equilibration. Numerics for a specific class of integrable quantum magnets, which does not fulfill the ETH, illustrate the findings.