Classical Estimation of the Free Energy and Quantum Gibbs Sampling from the Markov Entropy Decomposition

Fuente: arXiv
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Main Authors: Scalet, Samuel O., Capel, Angela, Chowdhury, Anirban N., Fawzi, Hamza, Fawzi, Omar, Kim, Isaac H., Tikku, Arkin
Format: Preprint
Published: 2025
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_version_ 1866915699038879744
author Scalet, Samuel O.
Capel, Angela
Chowdhury, Anirban N.
Fawzi, Hamza
Fawzi, Omar
Kim, Isaac H.
Tikku, Arkin
author_facet Scalet, Samuel O.
Capel, Angela
Chowdhury, Anirban N.
Fawzi, Hamza
Fawzi, Omar
Kim, Isaac H.
Tikku, Arkin
contents We revisit the Markov Entropy Decomposition, a classical convex relaxation algorithm introduced by Poulin and Hastings to approximate the free energy in quantum spin lattices. We identify a sufficient condition for its convergence, namely the decay of the effective interaction. The effective interaction, also known as Hamiltonians of mean force, is a widely established correlation measure, and we show our decay condition in 1D at any temperature as well as in the high-temperature regime under a certain commutativity condition on the Hamiltonian building on existing results. This yields polynomial and quasi-polynomial time approximation algorithms in these settings, respectively. Furthermore, the decay of the effective interaction implies the decay of the conditional mutual information for the Gibbs state of the system. We then use this fact to devise a rounding scheme that maps the solution of the convex relaxation to a global state and show that the scheme can be efficiently implemented on a quantum computer, thus proving efficiency of quantum Gibbs sampling under our assumption of decay of the effective interaction.
format Preprint
id arxiv_https___arxiv_org_abs_2504_17405
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Classical Estimation of the Free Energy and Quantum Gibbs Sampling from the Markov Entropy Decomposition
Scalet, Samuel O.
Capel, Angela
Chowdhury, Anirban N.
Fawzi, Hamza
Fawzi, Omar
Kim, Isaac H.
Tikku, Arkin
Quantum Physics
Statistical Mechanics
Mathematical Physics
We revisit the Markov Entropy Decomposition, a classical convex relaxation algorithm introduced by Poulin and Hastings to approximate the free energy in quantum spin lattices. We identify a sufficient condition for its convergence, namely the decay of the effective interaction. The effective interaction, also known as Hamiltonians of mean force, is a widely established correlation measure, and we show our decay condition in 1D at any temperature as well as in the high-temperature regime under a certain commutativity condition on the Hamiltonian building on existing results. This yields polynomial and quasi-polynomial time approximation algorithms in these settings, respectively. Furthermore, the decay of the effective interaction implies the decay of the conditional mutual information for the Gibbs state of the system. We then use this fact to devise a rounding scheme that maps the solution of the convex relaxation to a global state and show that the scheme can be efficiently implemented on a quantum computer, thus proving efficiency of quantum Gibbs sampling under our assumption of decay of the effective interaction.
title Classical Estimation of the Free Energy and Quantum Gibbs Sampling from the Markov Entropy Decomposition
topic Quantum Physics
Statistical Mechanics
Mathematical Physics
url https://arxiv.org/abs/2504.17405