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Emergent Ashkin-Teller criticality in a constrained boson model
by Anirudha Menon, Anwesha Chattopadhyay, K. Sengupta, Arnab Sen
Submission summary
Authors (as registered SciPost users): | Anwesha Chattopadhyay · Arnab Sen · Krishnendu Sengupta |
Submission information | |
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Preprint Link: | scipost_202411_00003v2 (pdf) |
Date submitted: | 2025-01-16 12:51 |
Submitted by: | Sengupta, Krishnendu |
Submitted to: | SciPost Physics |
Ontological classification | |
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Academic field: | Physics |
Specialties: |
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Approach: | Theoretical |
Abstract
We show, via explicit computation on a constrained bosonic model, that the presence of subsystem symmetries can lead to a quantum phase transition (QPT) where the critical point exhibits an emergent enhanced symmetry. Such a transition separates a unique gapped ground state from a gapless one; the latter phase exhibits a broken Z2 symmetry which we tie to the presence of the subsystem symmetries in the model. The intermediate critical point separating these phases exhibits an additional emergent Z2 symmetry which we identify; this emergence leads to a critical theory in the Ashkin-Teller, instead of the expected Ising, universality class. We show that the transitions of the model reproduces the Askhin-Teller critical line with variable correlation length exponent ν but constant central charge c. We verify this scenario via explicit exact-diagonalization computations, provide an effective Landau-Ginzburg theory for such a transition, and discuss the connection of our model to the PXP model describing Rydberg atom arrays.
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
List of changes
1) Added comments in Sec 2 regarding flat bands in diamond lattice in response to suggestions by the editor. Also added Ref 34.
2) Added comment in Sec 3 regarding quadratic energy dispersion of the model in the gapless phase in response to comment by Ref 2.
3) Added comment on diamond chain lattice in Sec 2 in response to suggestion by Ref 2.
4) Added ref 25 in response to comment by Ref 2.
5) Added a comment in the discussion section of the paper clarifying the notion of subsystem symmetry in response to comment by Ref 3.
6) Added Refs 38 and 39 in response to comment on Schrieffer-Wolfe transformation by Ref 3.
7) Added a discussion on the sign of the parameter α in Sec 2 in response to comment by Ref 3. Al;so added Refs 38 and 39 in this context.
Current status:
Reports on this Submission
Report
I appreciate the efforts made by the authors to improve the paper, but I am still not convinced that the claim of the Ashkin-Teller universality class is supported well enough. I believe that the operator content can be studied numerically in spite of the unclear relation to the microscopic operators mentioned by the author. I am also confused with the comment "a change in boundary condition may change c (central charge)" at the end of Section 5. I did check Ref. [45], and if you *define* the "effective central charge" as in Ref. [45] it would be true, but perhaps it is rather a misnomer. As a general principle, the boundary conditions should not alter the bulk universality class which is characterized by the central charge. If the author somehow implies that Ref. [45] is related to the claim of the (bulk) Ashkin-Teller universality class, I am afraid that they are mistaken.
It is also not clear to me how the discussion in Sec. 4.2 is related to the specific model in question.
On the other hand, as I mentioned, this paper does contain some interesting observations.
I would suggest two options:
1) Consult/collaborate with someone with a strong background of CFT to perform a more thorough comparison with CFT.
2) Revise the paper to objectively describe theoretically established statements and numerical observations. The authors may speculate/conjecture the Ashkin-Teller universality class in the Discussion section, but I think it better to remove the Ashkin-Teller from the title etc.
Recommendation
Ask for major revision