Experimental observation of a generalized Gibbs ensemble

Author(s): Tim Langen, S. Erne, Remi Geiger, B. Rauer, Thomas Schweigler, Maximilian Kuhnert, Wolfgang Rohringer, Igor Mazets, T. Gasenzer, J. Schmiedmayer

Journal: Science

Volume: 348

Page(s): 207-211

Year: 2015

DOI Number: 10.1126/science.1257026

Link: Link to publication


The description of the non-equilibrium dynamics of isolated quantum many-body systems within the framework of statistical mechanics is a fundamental open question. Conventional thermodynamical ensembles fail to describe the large class of systems that exhibit nontrivial conserved quantities, and generalized ensembles have been predicted to maximize entropy in these systems. We show experimentally that a degenerate one-dimensional Bose gas relaxes to a state that can be described by such a generalized ensemble. This is verified through a detailed study of correlation functions up to 10th order. The applicability of the generalized ensemble description for isolated quantum many-body systems points to a natural emergence of classical statistical properties from the microscopic unitary quantum evolution.

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