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Bistabilities and domain walls in weakly open quantum systems
by Florian Lange, Achim Rosch
This Submission thread is now published as
Submission summary
| Authors (as registered SciPost users): | Florian Lange · Achim Rosch |
| Submission information | |
|---|---|
| Preprint Link: | https://arxiv.org/abs/2007.08182v3 (pdf) |
| Date accepted: | 2020-10-06 |
| Date submitted: | 2020-09-15 11:43 |
| Submitted by: | Rosch, Achim |
| Submitted to: | SciPost Physics |
| Ontological classification | |
|---|---|
| Academic field: | Physics |
| Specialties: |
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| Approaches: | Theoretical, Computational, Phenomenological |
Abstract
Weakly pumped systems with approximate conservation laws can be efficiently described by a generalized Gibbs ensemble if the steady state of the system is unique. However, such a description can fail if there are multiple steady state solutions, for example, a bistability. In this case domains and domain walls may form. In one-dimensional (1D) systems any type of noise (thermal or non-thermal) will in general lead to a proliferation of such domains. We study this physics in a 1D spin chain with two approximate conservation laws, energy and the $z$-component of the total magnetization. A bistability in the magnetization is induced by the coupling to suitably chosen Lindblad operators. We analyze the theory for a weak coupling strength $\epsilon$ to the non-equilibrium bath. In this limit, we argue that one can use hydrodynamic approximations which describe the system locally in terms of space- and time-dependent Lagrange parameters. Here noise terms enforce the creation of domains, where the typical width of a domain wall goes as $\sim 1/\sqrt{\epsilon}$ while the density of domain walls is exponentially small in $1/\sqrt{\epsilon}$. This is shown by numerical simulations of a simplified hydrodynamic equation in the presence of noise.
Author comments upon resubmission
List of changes
In reply to the referees, we made a number of changes. The most important ones are the following:
1) p.8, a new paragraph "Formally, ...." has been added providing a formal justification why the simplified hydrodynamic equations
will reproduced the qualitative features of the full hydrodynamic approach
2) p.11, a new paragraph "While we..." in the conclusion also emphasized that the results apply to a large class of problems
3) p. 10, below Eq. (18), we improved the fitting procedure and added error bars to the results. The new appendix A.3 and Fig. 6 shows a similar analysis of the data obtained by omitting non-thermal noise.
4) Introductory sentence on p. 1 has been reformulated. Similarly, statements on dark states and on the 2nd law of thermodynamics on p . 2 and 8 have been reformulated.
5) Ref. [26] and [27] have been added
6) minor changes to Fig. 2 and Fig. 3 (data is not modified)
7) p. 7, a new header "Simplified hydrodynamic model: order parameter theory" has been used to structure the paper in a better way.
Published as SciPost Phys. 9, 057 (2020)
Reports on this Submission
Report #2 by Anonymous (Referee 5) on 2020-9-18 (Invited Report)
- Cite as: Anonymous, Report on arXiv:2007.08182v3, delivered 2020-09-18, doi: 10.21468/SciPost.Report.2008
Report
The revised version of the manuscript has improved significantly. In particular, all concrete issues from my first report have been addressed.
I would furthermore like to thank the authors for the clarifications not only via their revisions, but also their replies. Thanks to them, I recommend publication of the manuscript in its present form.
Requested changes
Pay attention to placement of figures (in particular Figs. 1 and 3) during production.