Eigenstate thermalization hypothesis beyond standard indicators: Emergence of random-matrix behavior at small frequencies

Jonas Richter, Anatoly Dymarsky, Robin Steinigeweg, Jochen Gemmer

Research output: Contribution to journalArticlepeer-review

41 Scopus citations

Abstract

Using numerical exact diagonalization, we study matrix elements of a local spin operator in the eigenbasis of two different nonintegrable quantum spin chains. Our emphasis is on the question to what extent local operators can be represented as random matrices and, in particular, to what extent matrix elements can be considered as uncorrelated. As a main result, we show that the eigenvalue distribution of band submatrices at a fixed energy density is a sensitive probe of the correlations between matrix elements. We find that, on the scales where the matrix elements are in a good agreement with all standard indicators of the eigenstate thermalization hypothesis, the eigenvalue distribution still exhibits clear signatures of the original operator, implying correlations between matrix elements. Moreover, we demonstrate that at much smaller energy scales, the eigenvalue distribution approximately assumes the universal semicircle shape, indicating transition to the random-matrix behavior, and in particular that matrix elements become uncorrelated.

Original languageEnglish
Article number042127
JournalPhysical Review E - Statistical, Nonlinear, and Soft Matter Physics
Volume102
Issue number4
DOIs
StatePublished - Oct 23 2020

Bibliographical note

Publisher Copyright:
© 2020 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

ASJC Scopus subject areas

  • Statistical and Nonlinear Physics
  • Statistics and Probability
  • Condensed Matter Physics

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