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Fusion of Low-Entanglement Excitations in 2D Toric Code

by Jing-Yu Zhao, Xie Chen

Submission summary

Authors (as registered SciPost users): Xie Chen · Jingyu Zhao
Submission information
Preprint Link: https://arxiv.org/abs/2409.07544v1  (pdf)
Date submitted: 2024-10-02 05:33
Submitted by: Zhao, Jingyu
Submitted to: SciPost Physics
Ontological classification
Academic field: Physics
Specialties:
  • Condensed Matter Physics - Theory
Approach: Theoretical

Abstract

On top of a $D$-dimensional gapped bulk state, Low Entanglement Excitations (LEE) on $d$($<D$)-dimensional sub-manifolds can have extensive energy but preserves the entanglement area law of the ground state. Due to their multi-dimensional nature, the LEEs embody a higher-category structure in quantum systems. They are the ground state of a modified Hamiltonian and hence capture the notions of `defects' of generalized symmetries. In previous works, we studied the low-entanglement excitations in a trivial phase as well as those in invertible phases. We find that LEEs in these phases have the same structure as lower-dimensional gapped phases and their defects within. In this paper, we study the LEEs inside non-invertible topological phases. We focus on the simple example of $\mathbb{Z}_2$ toric code and discuss how the fusion result of 1d LEEs with 0d morphisms can depend on both the choice of fusion circuit and the ordering of the fused defects.

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
Current status:
In refereeing

Reports on this Submission

Report #1 by Anonymous (Referee 1) on 2024-12-1 (Invited Report)

Strengths

Uncovers an interesting fusion rule of 1D Low-Entanglement Excitations and 0D morphisms in 2D and 3D toric code

Weaknesses

None

Report

The paper study the 0d and 1d Low-Entanglement Excitations in 2D and 3D toric codes. Using the language of quantum circuit, the authors discuss the fusion rule of low-entanglement excitations. In paticular, the non-commutative fusion rule in the 1d LEEs with nontrivial morphisms is very suprising and interesting. This implies a very detailed braided-fusion 2-category structure of Low-Entanglement Excitations in non-invertible topological phases.

The paper is clearly written, and contains new interesting results on algebra sturcture of 0d and 1d Low-Entanglement Excitations in 2D and 3D. Their fusion can be explicitly shown by constructing 0d unitary transformations or 1d circuits. It provides a insight into the algebra and entanglement nature of excitated states. Therefore, the referee recommends that the paper is published in SciPost.

Requested changes

None

Recommendation

Publish (easily meets expectations and criteria for this Journal; among top 50%)

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

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