Entropy Scaling Law and the Quantum Marginal Problem

Quantum many-body states that frequently appear in physics often obey an entropy scaling law, meaning that an entanglement entropy of a subsystem can be expressed as a sum of terms that scale linearly with its volume and area, plus a correction term that is independent of its size. We conjecture tha...

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Autor principal: Isaac H. Kim
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Publicado: American Physical Society 2021
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spelling oai:doaj.org-article:5d9e9921e48844a3855cdce4ae81f9d72021-12-02T14:44:23ZEntropy Scaling Law and the Quantum Marginal Problem10.1103/PhysRevX.11.0210392160-3308https://doaj.org/article/5d9e9921e48844a3855cdce4ae81f9d72021-05-01T00:00:00Zhttp://doi.org/10.1103/PhysRevX.11.021039http://doi.org/10.1103/PhysRevX.11.021039https://doaj.org/toc/2160-3308Quantum many-body states that frequently appear in physics often obey an entropy scaling law, meaning that an entanglement entropy of a subsystem can be expressed as a sum of terms that scale linearly with its volume and area, plus a correction term that is independent of its size. We conjecture that these states have an efficient dual description in terms of a set of marginal density matrices on bounded regions, obeying the same entropy scaling law locally. We prove a restricted version of this conjecture for translationally invariant systems in two spatial dimensions. Specifically, we prove that a translationally invariant marginal obeying three nonlinear constraints—all of which follow from the entropy scaling law straightforwardly—must be consistent with some global state on an infinite lattice. Moreover, we derive a closed-form expression for the maximum-entropy density compatible with those marginals, deriving a variational upper bound on the thermodynamic free energy. The main assumptions of our construction are satisfied exactly by solvable models of topological order and approximately by finite-temperature Gibbs states of certain quantum spin Hamiltonians.Isaac H. KimAmerican Physical SocietyarticlePhysicsQC1-999ENPhysical Review X, Vol 11, Iss 2, p 021039 (2021)
institution DOAJ
collection DOAJ
language EN
topic Physics
QC1-999
spellingShingle Physics
QC1-999
Isaac H. Kim
Entropy Scaling Law and the Quantum Marginal Problem
description Quantum many-body states that frequently appear in physics often obey an entropy scaling law, meaning that an entanglement entropy of a subsystem can be expressed as a sum of terms that scale linearly with its volume and area, plus a correction term that is independent of its size. We conjecture that these states have an efficient dual description in terms of a set of marginal density matrices on bounded regions, obeying the same entropy scaling law locally. We prove a restricted version of this conjecture for translationally invariant systems in two spatial dimensions. Specifically, we prove that a translationally invariant marginal obeying three nonlinear constraints—all of which follow from the entropy scaling law straightforwardly—must be consistent with some global state on an infinite lattice. Moreover, we derive a closed-form expression for the maximum-entropy density compatible with those marginals, deriving a variational upper bound on the thermodynamic free energy. The main assumptions of our construction are satisfied exactly by solvable models of topological order and approximately by finite-temperature Gibbs states of certain quantum spin Hamiltonians.
format article
author Isaac H. Kim
author_facet Isaac H. Kim
author_sort Isaac H. Kim
title Entropy Scaling Law and the Quantum Marginal Problem
title_short Entropy Scaling Law and the Quantum Marginal Problem
title_full Entropy Scaling Law and the Quantum Marginal Problem
title_fullStr Entropy Scaling Law and the Quantum Marginal Problem
title_full_unstemmed Entropy Scaling Law and the Quantum Marginal Problem
title_sort entropy scaling law and the quantum marginal problem
publisher American Physical Society
publishDate 2021
url https://doaj.org/article/5d9e9921e48844a3855cdce4ae81f9d7
work_keys_str_mv AT isaachkim entropyscalinglawandthequantummarginalproblem
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