Lowering the temperature of two-dimensional fermionic tensor networks with cluster expansions

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Hauptverfasser: De Meyer, Sander, Ueda, Atsushi, He, Yuchi, Bultinck, Nick, Haegeman, Jutho
Format: Preprint
Veröffentlicht: 2026
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author De Meyer, Sander
Ueda, Atsushi
He, Yuchi
Bultinck, Nick
Haegeman, Jutho
author_facet De Meyer, Sander
Ueda, Atsushi
He, Yuchi
Bultinck, Nick
Haegeman, Jutho
contents Representing the time-evolution operator as a tensor network constitutes a key ingredient in several algorithms for studying quantum lattice systems at finite temperature or in a non-equilibrium setting. For a Hamiltonian composed of strictly short-ranged interactions, the Suzuki-Trotter decomposition is the main technique for obtaining such a representation. In [B.~Vanhecke, L.~Vanderstraeten and F.~Verstraete, Physical Review A, L020402 (2021)], an alternative strategy, the cluster expansion, was introduced. This approach naturally preserves internal and lattice symmetries and can more easily be extended to higher-order representations or longer-ranged interactions. We extend the cluster expansion to two-dimensional fermionic systems, and employ it to construct projected entangled-pair operator (PEPO) approximations of Gibbs states. We also discuss and benchmark different truncation schemes for multiplying layers of PEPOs together. Applying the resulting framework to a two-dimensional spinless fermion model with attractive interactions, we resolve a clear phase boundary at finite temperature.
format Preprint
id arxiv_https___arxiv_org_abs_2602_22113
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Lowering the temperature of two-dimensional fermionic tensor networks with cluster expansions
De Meyer, Sander
Ueda, Atsushi
He, Yuchi
Bultinck, Nick
Haegeman, Jutho
Strongly Correlated Electrons
Quantum Physics
Representing the time-evolution operator as a tensor network constitutes a key ingredient in several algorithms for studying quantum lattice systems at finite temperature or in a non-equilibrium setting. For a Hamiltonian composed of strictly short-ranged interactions, the Suzuki-Trotter decomposition is the main technique for obtaining such a representation. In [B.~Vanhecke, L.~Vanderstraeten and F.~Verstraete, Physical Review A, L020402 (2021)], an alternative strategy, the cluster expansion, was introduced. This approach naturally preserves internal and lattice symmetries and can more easily be extended to higher-order representations or longer-ranged interactions. We extend the cluster expansion to two-dimensional fermionic systems, and employ it to construct projected entangled-pair operator (PEPO) approximations of Gibbs states. We also discuss and benchmark different truncation schemes for multiplying layers of PEPOs together. Applying the resulting framework to a two-dimensional spinless fermion model with attractive interactions, we resolve a clear phase boundary at finite temperature.
title Lowering the temperature of two-dimensional fermionic tensor networks with cluster expansions
topic Strongly Correlated Electrons
Quantum Physics
url https://arxiv.org/abs/2602.22113