Anomalies of average symmetries: entanglement and open quantum systems

Abstract Symmetries and their anomalies are powerful tools for understanding quantum systems. However, realistic systems are often subject to disorders, dissipation and decoherence. In many circumstances, symmetries are not exact but only on average. This work investigates the constraints on mixed s...

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Main Authors: Po-Shen Hsin, Zhu-Xi Luo, Hao-Yu Sun
Format: Article
Language:English
Published: SpringerOpen 2024-10-01
Series:Journal of High Energy Physics
Subjects:
Online Access:https://doi.org/10.1007/JHEP10(2024)134
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author Po-Shen Hsin
Zhu-Xi Luo
Hao-Yu Sun
author_facet Po-Shen Hsin
Zhu-Xi Luo
Hao-Yu Sun
author_sort Po-Shen Hsin
collection DOAJ
description Abstract Symmetries and their anomalies are powerful tools for understanding quantum systems. However, realistic systems are often subject to disorders, dissipation and decoherence. In many circumstances, symmetries are not exact but only on average. This work investigates the constraints on mixed states resulting from non-commuting average symmetries. We will focus on the cases where the commutation relations of the average symmetry generators are violated by nontrivial phases, and call such average symmetry anomalous. We show that anomalous average symmetry implies degeneracy in the density matrix eigenvalues, and present several lattice examples with average symmetries, including XY chain, Heisenberg chain, and deformed toric code models. In certain cases, the results can be further extended to reduced density matrices, leading to a new lower bound on the entanglement entropy. We discuss several applications in the contexts of many body localization, quantum channels, entanglement phase transitions and also derive new constraints on the Lindbladian evolution of open quantum systems.
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issn 1029-8479
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publishDate 2024-10-01
publisher SpringerOpen
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series Journal of High Energy Physics
spelling doaj-art-937e7a14f3ba4ef9b4af6b3be4b80a592024-12-08T12:11:14ZengSpringerOpenJournal of High Energy Physics1029-84792024-10-0120241014210.1007/JHEP10(2024)134Anomalies of average symmetries: entanglement and open quantum systemsPo-Shen Hsin0Zhu-Xi Luo1Hao-Yu Sun2Mani L. Bhaumik Institute for Theoretical Physics, Department of Physics and Astronomy, University of California Los AngelesDepartment of Physics, Harvard UniversityWeinberg Institute, Department of Physics, The University of Texas at AustinAbstract Symmetries and their anomalies are powerful tools for understanding quantum systems. However, realistic systems are often subject to disorders, dissipation and decoherence. In many circumstances, symmetries are not exact but only on average. This work investigates the constraints on mixed states resulting from non-commuting average symmetries. We will focus on the cases where the commutation relations of the average symmetry generators are violated by nontrivial phases, and call such average symmetry anomalous. We show that anomalous average symmetry implies degeneracy in the density matrix eigenvalues, and present several lattice examples with average symmetries, including XY chain, Heisenberg chain, and deformed toric code models. In certain cases, the results can be further extended to reduced density matrices, leading to a new lower bound on the entanglement entropy. We discuss several applications in the contexts of many body localization, quantum channels, entanglement phase transitions and also derive new constraints on the Lindbladian evolution of open quantum systems.https://doi.org/10.1007/JHEP10(2024)134Global SymmetriesTopological States of MatterWilson’t Hooft and Polyakov loopsDiscrete Symmetries
spellingShingle Po-Shen Hsin
Zhu-Xi Luo
Hao-Yu Sun
Anomalies of average symmetries: entanglement and open quantum systems
Journal of High Energy Physics
Global Symmetries
Topological States of Matter
Wilson
’t Hooft and Polyakov loops
Discrete Symmetries
title Anomalies of average symmetries: entanglement and open quantum systems
title_full Anomalies of average symmetries: entanglement and open quantum systems
title_fullStr Anomalies of average symmetries: entanglement and open quantum systems
title_full_unstemmed Anomalies of average symmetries: entanglement and open quantum systems
title_short Anomalies of average symmetries: entanglement and open quantum systems
title_sort anomalies of average symmetries entanglement and open quantum systems
topic Global Symmetries
Topological States of Matter
Wilson
’t Hooft and Polyakov loops
Discrete Symmetries
url https://doi.org/10.1007/JHEP10(2024)134
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AT zhuxiluo anomaliesofaveragesymmetriesentanglementandopenquantumsystems
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