Symmetry-resolved properties of the trace distance in thermalizing SU(2) systems

Fuente: arXiv
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Main Authors: Shen, Haojie, Chen, Jie, Wang, Xiaoqun
Format: Preprint
Published: 2026
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author Shen, Haojie
Chen, Jie
Wang, Xiaoqun
author_facet Shen, Haojie
Chen, Jie
Wang, Xiaoqun
contents We study diagnostics of thermalization in quantum many-body systems with global SU(2) symmetry, where the standard eigenstate thermalization hypothesis (ETH) is generalized to its non-Abelian form. As an eigenstate-level probe, we introduce a symmetry-resolved trace distance constructed from the block structure of the reduced density matrix. This block structure separates spin-sector probabilities from configurational fluctuations within each sector, naturally leading to a decomposition into a probability trace distance and a configurational trace distance. The microcanonical average of the former is bounded by fluctuations of the corresponding spin-sector probabilities within a microcanonical energy window, whereas the latter captures finer intra-sector fluctuations. In non-Abelian thermalizing systems, these spin-sector-probability fluctuations are constrained by the non-Abelian ETH and therefore become exponentially suppressed with system size. Numerical studies of the one-dimensional \(J_1\)--\(J_2\) Heisenberg chain are consistent with this picture and suggest that, in the thermal regime, the trace distance is asymptotically dominated by the configurational trace distance.
format Preprint
id arxiv_https___arxiv_org_abs_2603_26540
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Symmetry-resolved properties of the trace distance in thermalizing SU(2) systems
Shen, Haojie
Chen, Jie
Wang, Xiaoqun
Quantum Physics
Statistical Mechanics
We study diagnostics of thermalization in quantum many-body systems with global SU(2) symmetry, where the standard eigenstate thermalization hypothesis (ETH) is generalized to its non-Abelian form. As an eigenstate-level probe, we introduce a symmetry-resolved trace distance constructed from the block structure of the reduced density matrix. This block structure separates spin-sector probabilities from configurational fluctuations within each sector, naturally leading to a decomposition into a probability trace distance and a configurational trace distance. The microcanonical average of the former is bounded by fluctuations of the corresponding spin-sector probabilities within a microcanonical energy window, whereas the latter captures finer intra-sector fluctuations. In non-Abelian thermalizing systems, these spin-sector-probability fluctuations are constrained by the non-Abelian ETH and therefore become exponentially suppressed with system size. Numerical studies of the one-dimensional \(J_1\)--\(J_2\) Heisenberg chain are consistent with this picture and suggest that, in the thermal regime, the trace distance is asymptotically dominated by the configurational trace distance.
title Symmetry-resolved properties of the trace distance in thermalizing SU(2) systems
topic Quantum Physics
Statistical Mechanics
url https://arxiv.org/abs/2603.26540