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arXiv · 2503.09717

Disentangling anomaly-free symmetries of quantum spin chains

Sahand Seifnashri·Wilbur Shirley
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Abstract

We clarify the lore that anomaly-free symmetries are either on-site or can be transformed into on-site symmetries. We prove that any finite, internal, anomaly-free symmetry in a 1+1d lattice Hamiltonian system can be disentangled into an on-site symmetry by introducing ancillas and applying conjugation via a finite-depth quantum circuit. We provide an explicit construction of the disentangling circuit using Gauss's law operators and emphasize the necessity of adding ancillas. Our result establishes the converse to a generalized Lieb-Schultz-Mattis theorem by demonstrating that any anomaly-free symmetry admits a trivially gapped Hamiltonian.

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Sahand Seifnashri, Wilbur Shirley. 2025-03-12. Disentangling anomaly-free symmetries of quantum spin chains. https://doi.org/10.1103/bscj-r5tg

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