Measuring postquench entanglement entropy through density correlations

Abstract

Following a sudden change of interactions in an integrable system of one-dimensional fermions, we analyze the dependence of the static structure factor on the observation time after the quantum quench. At small waiting times after the quench, we map the system to noninteracting bosons such that we are able to extract their occupation numbers from the Fourier transform of the density-density correlation function, and use these to compute a bosonic entropy from a diagonal ensemble. By comparing this bosonic entropy with the asymptotic steady-state entanglement entropy per fermion computed with exact diagonalization, we find excellent agreement.Received 8 December 2021Revised 17 March 2022Accepted 22 March 2022DOI:https://doi.org/10.1103/PhysRevResearch.4.L022023Published 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.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasBosonizationCharge density wavesEntanglement entropyQuantum quenchTechniquesExact diagonalizationLuttinger liquid modelCondensed Matter, Materials & Applied PhysicsQuantum InformationStatistical Physics