Entropy of isolated quantum systems after a quench

Lea F. Santos, Anatoli Polkovnikov, Marcos Rigol

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130 Scopus citations


A diagonal entropy, which depends only on the diagonal elements of the system's density matrix in the energy representation, has been recently introduced as the proper definition of thermodynamic entropy in out-of-equilibrium quantum systems. We study this quantity after an interaction quench in lattice hard-core bosons and spinless fermions, and after a local chemical potential quench in a system of hard-core bosons in a superlattice potential. The former systems have a chaotic regime, where the diagonal entropy becomes equivalent to the equilibrium microcanonical entropy, coinciding with the onset of thermalization. The latter system is integrable. We show that its diagonal entropy is additive and different from the entropy of a generalized Gibbs ensemble, which has been introduced to account for the effects of conserved quantities at integrability.

Original languageEnglish (US)
Article number040601
JournalPhysical review letters
Issue number4
StatePublished - Jul 18 2011

All Science Journal Classification (ASJC) codes

  • General Physics and Astronomy


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