SciPost Submission Page

Fluctuations of work in realistic equilibrium states of quantum systems with conserved quantities

by J. Mur-Petit, A. Relaño, R. A. Molina and D. Jaksch

This is not the current version.

Submission summary

As Contributors: Jordi Mur-Petit
Preprint link: scipost_201910_00032v1
Date submitted: 2019-10-18
Submitted by: Mur-Petit, Jordi
Submitted to: SciPost Physics Proceedings
Proceedings issue: 24th European Few Body Conference (University of Surrey, U.K.)
Discipline: Physics
Subject area: Quantum Physics
Approaches: Theoretical, Computational

Abstract

The out-of-equilibrium dynamics of quantum systems is one of the most fascinating problems in physics, with outstanding open questions on issues such as relaxation to equilibrium. An area of particular interest concerns few-body systems, where quantum and thermal fluctuations are expected to be especially relevant. In this contribution, we present numerical results demonstrating the impact of conserved quantities (or ‘charges’) in the outcomes of out-of-equilibrium measurements starting from realistic equilibrium states on a few-body system implementing the Dicke model.

Current status:
Has been resubmitted


Submission & Refereeing History

Resubmission scipost_201910_00032v3 on 11 December 2019
Submission scipost_201910_00032v1 on 18 October 2019

Reports on this Submission

Report 1 by Arnau Rios Huguet on 2019-12-4 Invited Report

  • Cite as: Arnau Rios Huguet, Report on arXiv:scipost_201910_00032v1, delivered 2019-12-04, doi: 10.21468/SciPost.Report.1366

Strengths

1. Provides new results that are insightful in the context of equilibration in quantum systems
2. Describes well work done by authors and other in the past

Weaknesses

1. Some very minor issues could be discussed in more detail - but length was presumably a concern in the original write-up

Report

The manuscript "Fluctuations of work in realistic equilibrium states of quantum systems with conserved quantities" by Mur-Petit, Relaño, Molina and Jaksch is an interesting contribution that discusses the interplay between conserved charges, dynamics and statistical ensembles - all relevant topics in thermalization of few-body quantum states. In addition to providing a summary of previous results, this proceedings contribution expands on previous works from the authors (Ref [22]) using new simulations that challenge some of the previous existing assumptions. On this basis alone, and the quality of the manuscript, I would normally be happy to accept this contribution to SciPost for the 24th European Few Body Conference. Having said that, I would like to ask clarification of some very minor issues before the paper is fully accepted.

Requested changes

The issues are listed below in order of appearance in the manuscript and I am sure the authors will be able to tackle them quickly in a new iteration of the manuscript:

1) Lines 23-24: "cooling of neutron stars" and "excess heat from chips": these two examples of thermalization are very specific. Can the author provide references that link these to the problem discussed here?

2) Notation in the protocol described in lines 93-104: I would have initially envisaged that the eigenstates of the system were defined not only by the quantum number associated to H, |n>, but also by the quantum numbers of the operators that commute with it - eg |n, k_1, k_2 ... k_{N'_cons} > . Are the k_i labels suppressed here for simplicity? I suppose that upon projecting on the energy, without specifying M_k, the eigenstates |n> will be a mixture of the different k_i eigenstates, which are then further distilled in each projection over M_k. Is this correct?

3) Still within the protocol, the authors do not state any prescription for the driving mechanism out of equilibrium. What is the time dependence in H(t) (or, equivalently, in U(t)), while joining the initial and final states? Are there any timescales or specific shapes that could be relevant in this switching procedure? I presume continuity in t is, for instance, a prerequisitie. One also presumably needs to be in a non-adiabatic regime to guarantee a non-equilibrated final state, in the context of the extended calculations presented here?

4) Line 148: there seems to be a missing reference between "see...; " & "otherwise"

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

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