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Entanglement in a fermion chain under continuous monitoring

by Xiangyu Cao, Antoine Tilloy, Andrea De Luca

Submission summary

As Contributors: Xiangyu Cao · Andrea De Luca
Arxiv Link: (pdf)
Date accepted: 2019-08-12
Date submitted: 2019-08-02
Submitted by: Cao, Xiangyu
Submitted to: SciPost Physics
Discipline: Physics
Subject area: Quantum Physics
Approaches: Theoretical, Computational


We study the entanglement entropy of the quantum trajectories of a free fermion chain under continuous monitoring of local occupation numbers. We propose a simple theory for entanglement entropy evolution from disentangled and highly excited initial states. It is based on generalized hydrodynamics and the quasi-particle pair approach to entanglement in integrable systems. We test several quantitative predictions of the theory against extensive numerics and find good agreement. In particular, the volume law entanglement is destroyed by the presence of arbitrarily weak measurement.

Ontology / Topics

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Entanglement Free fermions Quasiparticles

Published as SciPost Phys. 7, 024 (2019)

Author comments upon resubmission

Dear Editor and Referees,

We are thankful for your interest in the manuscript and helpful comments.

In the submitted revision, we strived to address all your suggestions. In particular, we added two new figures. Please see the list of changes for details.

We hope that the revised manuscript meets the criteria of SciPost.

Yours sincerely,

List of changes

major changes:
- added a figure on the entanglement growth with unitary unravelling to support the discussion (point 6 of Report 1).
- added a figure on the two-point mutual information of some representative quantum trajectories and discussed the meaning of the result (point 4 of Report 1).
- removed the previous flawed calculation in section 2 on the evolution of tensor squared.
Used instead a simpler argument (inspired by the referee's suggestion) to make our point (point 5 of Report 2).
- added a paragraph in introduction discussing significance of our study from the perspective of simulation of open quantum systems (point 1-2 of Report 1).

- fixed points 1 - 4 of Report 2.
- removed "good" from the footnote, following point 3 of Report 1.
- adding an explanation why fixing \lambda = 1/2 is ok (changing it and \gamma amounts to rescaling time; point 5 of Report 1).

Reports on this Submission

Anonymous Report 2 on 2019-8-10 Invited Report


Authors have addressed my questions/suggestions and I recommend publication of the manuscript.

  • validity: -
  • significance: -
  • originality: -
  • clarity: -
  • formatting: -
  • grammar: -

Anonymous Report 1 on 2019-8-2 Invited Report


I am satisfied with the changes made by the Authors and I recommend publication of the manuscript in SciPost.

  • validity: -
  • significance: -
  • originality: -
  • clarity: -
  • formatting: -
  • grammar: -

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