Complete Generalized Gibbs Ensembles in an Interacting Theory

• Published in: Physical review letters Vol. 115; no. 15; p. 157201
• Main Authors: Ilievski, E, De Nardis, J, Wouters, B, Caux, J-S, Essler, F H L, Prosen, T
• Format: Journal Article
• Language: English
• Published: United States 09.10.2015
• ISSN: 1079-7114
• DOI: 10.1103/physrevlett.115.157201

In integrable many-particle systems, it is widely believed that the stationary state reached at late times after a quantum quench can be described by a generalized Gibbs ensemble (GGE) constructed from their extensive number of conserved charges. A crucial issue is then to identify a complete set of these charges, enabling the GGE to provide exact steady-state predictions. Here we solve this long-standing problem for the case of the spin-1/2 Heisenberg chain by explicitly constructing a GGE which uniquely fixes the macrostate describing the stationary behavior after a general quantum quench. A crucial ingredient in our method, which readily generalizes to other integrable models, are recently discovered quasilocal charges. As a test, we reproduce the exact postquench steady state of the Néel quench problem obtained previously by means of the Quench Action method.