Average entanglement entropy of a small subsystem in a constrained pure Gaussian state ensemble

Fuente: arXiv
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Main Authors: Aurell, Erik, Hackl, Lucas, Kieburg, Mario
Format: Preprint
Published: 2025
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author Aurell, Erik
Hackl, Lucas
Kieburg, Mario
author_facet Aurell, Erik
Hackl, Lucas
Kieburg, Mario
contents We consider ensembles of pure Gaussian states parametrized by single-mode marginals and (optionally) specific mode-mode correlations. Such ensembles provide a model for the final states when isolated quantum systems thermalize, as they can reproduce thermal properties locally, while being globally pure. By an analysis using real replicas and the coherent state representation of Gaussian states we show that the average entanglement entropy of a small subsystem is the same as the von Neumann entropy of a mixed Gaussian state with the same marginals, but no correlations. Finally, we discuss how these ensembles provide a model for Hawking radiation assuming unitary evolution, and discuss some of their properties in relations to the Page curve of Hawking radiation.
format Preprint
id arxiv_https___arxiv_org_abs_2505_03696
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Average entanglement entropy of a small subsystem in a constrained pure Gaussian state ensemble
Aurell, Erik
Hackl, Lucas
Kieburg, Mario
Quantum Physics
Statistical Mechanics
General Relativity and Quantum Cosmology
We consider ensembles of pure Gaussian states parametrized by single-mode marginals and (optionally) specific mode-mode correlations. Such ensembles provide a model for the final states when isolated quantum systems thermalize, as they can reproduce thermal properties locally, while being globally pure. By an analysis using real replicas and the coherent state representation of Gaussian states we show that the average entanglement entropy of a small subsystem is the same as the von Neumann entropy of a mixed Gaussian state with the same marginals, but no correlations. Finally, we discuss how these ensembles provide a model for Hawking radiation assuming unitary evolution, and discuss some of their properties in relations to the Page curve of Hawking radiation.
title Average entanglement entropy of a small subsystem in a constrained pure Gaussian state ensemble
topic Quantum Physics
Statistical Mechanics
General Relativity and Quantum Cosmology
url https://arxiv.org/abs/2505.03696