Algorithmic Locality via Provable Convergence in Quantum Tensor Networks

Fuente: arXiv
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Main Authors: Midha, Siddhant, Zhang, Yifan F., Malz, Daniel, Abanin, Dmitry A., Gopalakrishnan, Sarang
Format: Preprint
Published: 2026
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author Midha, Siddhant
Zhang, Yifan F.
Malz, Daniel
Abanin, Dmitry A.
Gopalakrishnan, Sarang
author_facet Midha, Siddhant
Zhang, Yifan F.
Malz, Daniel
Abanin, Dmitry A.
Gopalakrishnan, Sarang
contents Belief propagation has recently emerged as a powerful framework for evaluating tensor networks in higher dimensions, combining computational efficiency with provable analytical guarantees. In this work, we develop the first end-to-end theory of tensor network belief propagation for a class of projected entangled pair states satisfying \emph{strong injectivity}. We show that when the injectivity parameter exceeds a constant threshold, BP fixed points can be found efficiently, and a cluster-corrected BP algorithm computes physical quantities to $1/\mathrm{poly}(N)$ error in $\mathrm{poly}(N)$ time for an $N$ qubit system. We identify a striking phenomenon we term \emph{algorithmic locality}: local perturbations of the tensor network affect the BP fixed point with an influence decaying rapidly with distance. As a result, updates to the fixed point after a local perturbation can be carried out using only local recomputation. Moreover, through the cluster expansion, this locality extends to observables, implying that local expectation values can be approximated from local data with controlled accuracy. Our results provide the first rigorous guarantee for the effectiveness of tensor-network belief propagation on a wide class of many-body states, bridging a gap between widely used numerical practice and provable algorithmic performance.
format Preprint
id arxiv_https___arxiv_org_abs_2604_21919
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Algorithmic Locality via Provable Convergence in Quantum Tensor Networks
Midha, Siddhant
Zhang, Yifan F.
Malz, Daniel
Abanin, Dmitry A.
Gopalakrishnan, Sarang
Quantum Physics
Statistical Mechanics
Mathematical Physics
Belief propagation has recently emerged as a powerful framework for evaluating tensor networks in higher dimensions, combining computational efficiency with provable analytical guarantees. In this work, we develop the first end-to-end theory of tensor network belief propagation for a class of projected entangled pair states satisfying \emph{strong injectivity}. We show that when the injectivity parameter exceeds a constant threshold, BP fixed points can be found efficiently, and a cluster-corrected BP algorithm computes physical quantities to $1/\mathrm{poly}(N)$ error in $\mathrm{poly}(N)$ time for an $N$ qubit system. We identify a striking phenomenon we term \emph{algorithmic locality}: local perturbations of the tensor network affect the BP fixed point with an influence decaying rapidly with distance. As a result, updates to the fixed point after a local perturbation can be carried out using only local recomputation. Moreover, through the cluster expansion, this locality extends to observables, implying that local expectation values can be approximated from local data with controlled accuracy. Our results provide the first rigorous guarantee for the effectiveness of tensor-network belief propagation on a wide class of many-body states, bridging a gap between widely used numerical practice and provable algorithmic performance.
title Algorithmic Locality via Provable Convergence in Quantum Tensor Networks
topic Quantum Physics
Statistical Mechanics
Mathematical Physics
url https://arxiv.org/abs/2604.21919