Variational Neural and Tensor Network Approximations of Thermal States

Fuente: arXiv
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Auteurs principaux: Lu, Sirui, Giudice, Giacomo, Cirac, J. Ignacio
Format: Preprint
Publié: 2024
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author Lu, Sirui
Giudice, Giacomo
Cirac, J. Ignacio
author_facet Lu, Sirui
Giudice, Giacomo
Cirac, J. Ignacio
contents We introduce a variational Monte Carlo algorithm for approximating finite-temperature quantum many-body systems, based on the minimization of a modified free energy. This approach directly approximates the state at a fixed temperature, allowing for systematic improvement of the ansatz expressiveness without accumulating errors from iterative imaginary time evolution. We employ a variety of trial states -- both tensor networks as well as neural networks -- as variational Ansätze for our numerical optimization. We benchmark and compare different constructions in the above classes, both for one- and two-dimensional problems, with systems made of up to $N=100$ spins. Our results demonstrate that while restricted Boltzmann machines show limitations, string bond tensor network states exhibit systematic improvements with increasing bond dimensions and the number of strings.
format Preprint
id arxiv_https___arxiv_org_abs_2401_14243
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Variational Neural and Tensor Network Approximations of Thermal States
Lu, Sirui
Giudice, Giacomo
Cirac, J. Ignacio
Quantum Physics
Disordered Systems and Neural Networks
Strongly Correlated Electrons
We introduce a variational Monte Carlo algorithm for approximating finite-temperature quantum many-body systems, based on the minimization of a modified free energy. This approach directly approximates the state at a fixed temperature, allowing for systematic improvement of the ansatz expressiveness without accumulating errors from iterative imaginary time evolution. We employ a variety of trial states -- both tensor networks as well as neural networks -- as variational Ansätze for our numerical optimization. We benchmark and compare different constructions in the above classes, both for one- and two-dimensional problems, with systems made of up to $N=100$ spins. Our results demonstrate that while restricted Boltzmann machines show limitations, string bond tensor network states exhibit systematic improvements with increasing bond dimensions and the number of strings.
title Variational Neural and Tensor Network Approximations of Thermal States
topic Quantum Physics
Disordered Systems and Neural Networks
Strongly Correlated Electrons
url https://arxiv.org/abs/2401.14243