# Relaxation and entropy generation after quenching quantum spin chains

### Submission summary

 As Contributors: Gabor Takacs Arxiv Link: https://arxiv.org/abs/2004.09550v3 (pdf) Date accepted: 2020-07-13 Date submitted: 2020-06-25 Submitted by: Takacs, Gabor Submitted to: SciPost Physics Discipline: Physics Subject area: Quantum Physics Approaches: Theoretical, Computational

### Abstract

This work considers entropy generation and relaxation in quantum quenches in the Ising and $3$-state Potts spin chains. In the absence of explicit symmetry breaking we find universal ratios involving R\'enyi entropy growth rates and magnetisation relaxation for small quenches. We also demonstrate that the magnetisation relaxation rate provides an observable signature for the "dynamical Gibbs effect" which is a recently discovered characteristic non-monotonous behaviour of entropy growth linked to changes in the quasi-particle spectrum.

###### Current status:
Publication decision taken: accept

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

Dear Editor,

hereby I resubmit the revised version of our paper entitled "Relaxation and entropy generation after quenching quantum spin chains". We thank the referees for their suggestions. The changes made in reply are listed below.

Yours faithfully,

Gabor Takacs

### List of changes

To report 1:
1. We changed the notation for the fermion mass to capital M.
2. We agree with the comment, and accordingly added the word "some" in the sentence.
3.-4. Again, we agree with the suggestions for clarification, and changed the sentence accordingly.
5. Indeed, the sentence ended unclear after editing. We split and reformulated it, to make its meaning clear.

To report 2:
1. We added a short subsection 3.3, which defines what we mean exactly by semi-locality, and the parallel between the order parameter and the branch point twist field in this regard. In this process we also added some references.
2. We thank the referee for pointing out the new result. We added the reference and modified the sentence accordingly.

Additionally, we also updated reference [43] (O. A. Castro-Alvaredo et al.: Entanglement Oscillations near a Quantum Critical Point), which has appeared in Phys. Rev. Lett.

### Submission & Refereeing History

Resubmission 2004.09550v3 on 25 June 2020
Submission 2004.09550v2 on 1 May 2020

## Reports on this Submission

### Strengths

See my 1st Report

### Weaknesses

See my 1st Report

### Report

When I first reported on this paper I was very positive about it and had only small suggestions for the authors. I can see that they have taken then seriously and have made small improvements.

As before, I think this is a good paper that makes a valuable and timely contribution to the study of the out-of-equilibrium dynamics of entanglement.

### Requested changes

None

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