Efficient Eigenstate Preparation in an Integrable Model with Hilbert Space Fragmentation

We demonstrate that eigenstates of selected interacting spin chains can be efficiently prepared using quantum circuits with polynomial depth in system size and particle number. While this is well established for free-fermionic spin chains, we extend this result to the folded XXZ model, an integrable...

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Main Authors: Roberto Ruiz, Alejandro Sopena, Balázs Pozsgay, Esperanza López
Format: Article
Language:English
Published: American Physical Society 2025-07-01
Series:PRX Quantum
Online Access:http://doi.org/10.1103/g9f9-p8ks
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author Roberto Ruiz
Alejandro Sopena
Balázs Pozsgay
Esperanza López
author_facet Roberto Ruiz
Alejandro Sopena
Balázs Pozsgay
Esperanza López
author_sort Roberto Ruiz
collection DOAJ
description We demonstrate that eigenstates of selected interacting spin chains can be efficiently prepared using quantum circuits with polynomial depth in system size and particle number. While this is well established for free-fermionic spin chains, we extend this result to the folded XXZ model, an integrable rigid-rod deformation of the XX model with simple interactions that exhibits Hilbert space fragmentation. We construct explicit quantum circuits that efficiently prepare arbitrary eigenstates of this model on an open chain. Error-mitigated noisy simulations with up to 13 qubits and various qubit connectivities achieve a relative error below 5%. As a byproduct, we extend a recent reformulation of the Bethe ansatz as a quantum circuit to open boundary conditions.
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publisher American Physical Society
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spelling doaj-art-9cc28b5976104e5cb47a24b2178b4cea2025-08-20T02:48:01ZengAmerican Physical SocietyPRX Quantum2691-33992025-07-016303031610.1103/g9f9-p8ksEfficient Eigenstate Preparation in an Integrable Model with Hilbert Space FragmentationRoberto RuizAlejandro SopenaBalázs PozsgayEsperanza LópezWe demonstrate that eigenstates of selected interacting spin chains can be efficiently prepared using quantum circuits with polynomial depth in system size and particle number. While this is well established for free-fermionic spin chains, we extend this result to the folded XXZ model, an integrable rigid-rod deformation of the XX model with simple interactions that exhibits Hilbert space fragmentation. We construct explicit quantum circuits that efficiently prepare arbitrary eigenstates of this model on an open chain. Error-mitigated noisy simulations with up to 13 qubits and various qubit connectivities achieve a relative error below 5%. As a byproduct, we extend a recent reformulation of the Bethe ansatz as a quantum circuit to open boundary conditions.http://doi.org/10.1103/g9f9-p8ks
spellingShingle Roberto Ruiz
Alejandro Sopena
Balázs Pozsgay
Esperanza López
Efficient Eigenstate Preparation in an Integrable Model with Hilbert Space Fragmentation
PRX Quantum
title Efficient Eigenstate Preparation in an Integrable Model with Hilbert Space Fragmentation
title_full Efficient Eigenstate Preparation in an Integrable Model with Hilbert Space Fragmentation
title_fullStr Efficient Eigenstate Preparation in an Integrable Model with Hilbert Space Fragmentation
title_full_unstemmed Efficient Eigenstate Preparation in an Integrable Model with Hilbert Space Fragmentation
title_short Efficient Eigenstate Preparation in an Integrable Model with Hilbert Space Fragmentation
title_sort efficient eigenstate preparation in an integrable model with hilbert space fragmentation
url http://doi.org/10.1103/g9f9-p8ks
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AT alejandrosopena efficienteigenstatepreparationinanintegrablemodelwithhilbertspacefragmentation
AT balazspozsgay efficienteigenstatepreparationinanintegrablemodelwithhilbertspacefragmentation
AT esperanzalopez efficienteigenstatepreparationinanintegrablemodelwithhilbertspacefragmentation