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Dissipative quantum North-East-Center model: steady-state phase diagram, universality and nonergodic dynamics
by Pietro Brighi, Alberto Biella
Submission summary
| Authors (as registered SciPost users): | Alberto Biella · Pietro Brighi |
| Submission information | |
|---|---|
| Preprint Link: | scipost_202511_00035v1 (pdf) |
| Date submitted: | Nov. 17, 2025, 5:53 p.m. |
| Submitted by: | Pietro Brighi |
| Submitted to: | SciPost Physics |
| Ontological classification | |
|---|---|
| Academic field: | Physics |
| Specialties: |
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| Approaches: | Theoretical, Computational |
Abstract
In this work we study the dissipative quantum North-East-Center (NEC) model: a two-dimensional spin-1/2 lattice subject to chiral, kinetically constrained dissipation and coherent quantum interactions. This model combines kinetic constraints and chirality at the dissipative level, implementing local incoherent spin flips conditioned by an asymmetric majority-vote rule. Through a cluster mean-field approach, we determine the steady-state phase diagram of the NEC model under different Hamiltonians, consistently revealing the emergence of two distinct phases, bistable and normal, across all cases considered. We further investigate the stability of the steady-state with respect to inhomogeneous fluctuations in both phases, showing the emergence of instabilities at finite wavevectors in the proximity of the phase transition. Next, we study the nonergodicity of the model in the bistable phase. We characterize the dynamics of minority islands of spins surrounded by a large background of spins pointing in the opposite direction. We show that in the bistable phase, the minority islands are always reabsorbed by the surrounding at a constant velocity, irrespectively of their size. Finally, we propose and numerically benchmark an equation of motion for the reabsorption velocity of the islands where thermal and quantum fluctuations act independently at linear order.
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 carefully read the referee reports together with your assessment of the Manuscript.
We are happy to see that two out of three reports consider the paper suitable for SciPost Physics after major and minor revisions, respectively. However, the first referee feels that the paper is more suitable for SciPost Physics Core.
We argue that the paper is well-suited for SciPost Physics since it presents a significant advance on an important class of dissipative spin lattices featuring bistability and collective behaviours. We feel that in the previous version of the manuscript we did not stress enough how we go beyond the existing literature, specifically with respect to the Ref.[45].
To this aim in the revised version we commented clearly about this point in the Introduction. Also, we detailed our claims in the reply to Referee three. Here we report the main points:
We go systematically beyond the variational ansatz proposed in Ref.[45] by means of the cluster mean field approach (extensively used in the literature for 2D dissipative spin lattices).
Equipped with this tool we determine the structure of the phase diagram and quantitatively locate its boundaries. In the revised version of the Manuscript we also included simulation for a 4X4 plaquette, that is numerically the state of the art.
We identify the mechanisms responsible for the bubble reabsorptions and we propose an equation for their dynamics that we validate numerically (developing a non-translationally invariant version of the cluster mean-field ansatz).
We hope that the revised version of the Manuscript can be now considered suitable for publication in SciPost Physics.
Best regards
List of changes
List of the main changes :
1) In the Introduction we now briefly describe the important advancements with respect to Ref.[45]. 2) Following the referee suggestions we included the analysis of a larger plaquette made of 4X4 sites. 3) We clarified the meaning of the stability analysis, adding a more detailed connection with the cluster mean-field analysis and extending the Appendix with derivation of the equations in the main text. 4) We included all changes requested by the referees regarding figures formatting and other smaller issues.
Current status:
Reports on this Submission
Strengths
1- careful analysis of a dissipative quantum system displaying bistability.
Weaknesses
1- special model 2- cluster mean-field analysis neglecting fluctuations between clusters
Report
In this respect, it clearly has become publishable. But I see the progress made in this work with respect to literature more incremental than seminal. In view of this and the quite special model for which no experiments are envisaged I do not see one of the four acceptance criteria (expectations) fulfilled. So I recommend publication in SciPost Physics Core.
Recommendation
Accept in alternative Journal (see Report)
Report
Recommendation
Publish (meets expectations and criteria for this Journal)