Symmetry-driven thermalization via finite de Finetti theorems

Fuente: arXiv
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Main Authors: Singh, Uttam, Cerf, Nicolas J.
Format: Preprint
Published: 2026
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author Singh, Uttam
Cerf, Nicolas J.
author_facet Singh, Uttam
Cerf, Nicolas J.
contents Thermal behavior in subsystems of closed quantum systems is commonly attributed to dynamical chaos, quantum ergodicity, canonical typicality, or the eigenstate thermalization hypothesis, suggesting a fundamentally statistical origin of thermalization. Here, we propose a potential alternative mechanism in which thermal structures emerge deterministically from symmetry considerations alone, without recourse to statistical arguments. We prove a finite de Finetti-type theorem for quantum states invariant under energy-preserving unitaries, establishing that the reduced marginals of any such invariant $N$-qudit state are close (both in trace distance and relative entropy) to convex mixtures of thermal product states, with explicit error bounds vanishing as $N \to \infty$. We further present an example of energy-conserving Lindblad dynamics whose long-time limit is invariant under energy-preserving unitaries, providing a dynamical realization of the desired symmetry class. These results imply that invariance under energy-preserving unitaries suffices as a sole fundamental, deterministic principle to enforce thermal structures.
format Preprint
id arxiv_https___arxiv_org_abs_2604_09410
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Symmetry-driven thermalization via finite de Finetti theorems
Singh, Uttam
Cerf, Nicolas J.
Quantum Physics
Mathematical Physics
Thermal behavior in subsystems of closed quantum systems is commonly attributed to dynamical chaos, quantum ergodicity, canonical typicality, or the eigenstate thermalization hypothesis, suggesting a fundamentally statistical origin of thermalization. Here, we propose a potential alternative mechanism in which thermal structures emerge deterministically from symmetry considerations alone, without recourse to statistical arguments. We prove a finite de Finetti-type theorem for quantum states invariant under energy-preserving unitaries, establishing that the reduced marginals of any such invariant $N$-qudit state are close (both in trace distance and relative entropy) to convex mixtures of thermal product states, with explicit error bounds vanishing as $N \to \infty$. We further present an example of energy-conserving Lindblad dynamics whose long-time limit is invariant under energy-preserving unitaries, providing a dynamical realization of the desired symmetry class. These results imply that invariance under energy-preserving unitaries suffices as a sole fundamental, deterministic principle to enforce thermal structures.
title Symmetry-driven thermalization via finite de Finetti theorems
topic Quantum Physics
Mathematical Physics
url https://arxiv.org/abs/2604.09410