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Non-abelian symmetry-resolved entanglement entropy

by Eugenio Bianchi, Pietro Dona, Rishabh Kumar

Submission summary

Authors (as registered SciPost users): Eugenio Bianchi
Submission information
Preprint Link: scipost_202405_00030v2  (pdf)
Date accepted: 2024-10-21
Date submitted: 2024-10-03 19:03
Submitted by: Bianchi, Eugenio
Submitted to: SciPost Physics
Ontological classification
Academic field: Physics
Specialties:
  • Quantum Physics
Approach: Theoretical

Abstract

We introduce a mathematical framework for symmetry-resolved entanglement entropy with a non-abelian symmetry group. To obtain a reduced density matrix that is block-diagonal in the non-abelian charges, we define subsystems operationally in terms of subalgebras of invariant observables. We derive exact formulas for the average and the variance of the typical entanglement entropy for the ensemble of random pure states with fixed non-abelian charges. We focus on compact, semisimple Lie groups. We show that, compared to the abelian case, new phenomena arise from the interplay of locality and non-abelian symmetry, such as the asymmetry of the entanglement entropy under subsystem exchange, which we show in detail by computing the Page curve of a many-body system with SU(2) symmetry.

Author indications on fulfilling journal expectations

  • Provide a novel and synergetic link between different research areas.
  • Open a new pathway in an existing or a new research direction, with clear potential for multi-pronged follow-up work
  • Detail a groundbreaking theoretical/experimental/computational discovery
  • Present a breakthrough on a previously-identified and long-standing research stumbling block

Author comments upon resubmission

We thank the referees for their their careful reading of the manuscript and the feedback that helped us improve the presentation. In the new version, we have carefully addressed each of the concerns and comments raised by the referees by expanding significantly a subsection, adding a new table, adding references, and including clarifying remarks that improve the clarity of the presentation. In the replies, we provide a detailed response to each of the referees's comments.

List of changes

List of changes:
- Added remarks;
- Added table;
- Typos fixed;
- References added.
To help identifying the changes we highlighted them in red in the version attached to the referee responses.

Current status:
Accepted in target Journal

Editorial decision: For Journal SciPost Physics: Publish
(status: Editorial decision fixed and (if required) accepted by authors)


Reports on this Submission

Report #2 by Anonymous (Referee 2) on 2024-10-6 (Invited Report)

Report

I thank the authors for implementing the requested changes. I think that the further explanations and the comparisons with the existing literature have significantly improved the clarity of the paper and I recommend it for publication.

Recommendation

Publish (easily meets expectations and criteria for this Journal; among top 50%)

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

Report #1 by Anonymous (Referee 1) on 2024-10-6 (Invited Report)

Strengths

Same as in my first report

Weaknesses

The main weakness for me was that the mathematical nature of the work obscured the physical applications. This has been improved considerably in the 2nd version.

Report

The authors have submitted a revised version of their paper which answers my (minor) comments and those of the other referee. We both had rather similar comment in fact and the authors have made a considerable effort to comment on those, in particular to explain more clearly what they compute and how it might apply to specific types of theories. I recommend that the paper is now published.

Requested changes

None.

Recommendation

Publish (easily meets expectations and criteria for this Journal; among top 50%)

  • validity: top
  • significance: high
  • originality: top
  • clarity: top
  • formatting: excellent
  • grammar: excellent

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