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Research in out-of-equilibrium quantum physics has recently revealed relaxation towards a non-thermal statistical ensemble (Generalised Gibbs Ensemble or shortly GGE) that retains more memory of the initial state than the conventional thermal ensemble. The information content of this ensemble remains however a riddle. By analytically studying the time evolution after abrupt changes (quantum quenches) in extended one-dimensional quantum systems, we demonstrate relaxation according to the GGE in various different settings and specify the information that survives in the stationary state. In the case of evolution under a gapless non-interacting Hamiltonian on the other hand, we observe the failure of the GGE and find evidence of a novel type of equilibration characterised by the preservation of non-Gaussian correlations of the initial state. We propose an experimental check of our predictions based on current experimental techniques.

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Spiros Sotiriadis, University of Pisa
Seminarroom 0.02, ETP
Contact: Sebastian Diehl