Preparing valence-bond-solid states on noisy intermediate-scale quantum computers

Quantum state preparation is a key step in all digital quantum simulation algorithms. Here we propose methods to initialize on a gate-based quantum computer a general class of quantum spin wave functions, the so-called valence-bond-solid (VBS) states, that are important for two reasons. First, VBS s...

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Main Authors: Bruno Murta, Pedro M. Q. Cruz, J. Fernández-Rossier
Format: Article
Language:English
Published: American Physical Society 2023-03-01
Series:Physical Review Research
Online Access:http://doi.org/10.1103/PhysRevResearch.5.013190
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author Bruno Murta
Pedro M. Q. Cruz
J. Fernández-Rossier
author_facet Bruno Murta
Pedro M. Q. Cruz
J. Fernández-Rossier
author_sort Bruno Murta
collection DOAJ
description Quantum state preparation is a key step in all digital quantum simulation algorithms. Here we propose methods to initialize on a gate-based quantum computer a general class of quantum spin wave functions, the so-called valence-bond-solid (VBS) states, that are important for two reasons. First, VBS states are the exact ground states of a class of interacting quantum spin models introduced by Affleck, Kennedy, Lieb, and Tasaki (AKLT). Second, the two-dimensional VBS states are universal resource states for measurement-based quantum computing. We find that schemes to prepare VBS states based on their tensor-network representations yield quantum circuits that are too deep to be within reach of noisy intermediate-scale quantum (NISQ) computers. We then apply the general nondeterministic method herein proposed to the preparation of the spin-1 and spin-3/2 VBS states, the ground states of the AKLT models defined in one dimension and in the honeycomb lattice, respectively. Shallow quantum circuits of depth independent of the lattice size are explicitly derived for both cases, making use of optimization schemes that outperform standard basis gate decomposition methods. The probabilistic nature of the proposed routine translates into an average number of repetitions to successfully prepare the VBS state that scales exponentially with the number of lattice sites N. However, two strategies to quadratically reduce this repetition overhead for any bipartite lattice are devised. Our approach should permit to use NISQ processors to explore the AKLT model and variants thereof, outperforming conventional numerical methods in the near future.
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spelling doaj.art-823db52992c84daa8360f14499925be22024-04-12T17:29:24ZengAmerican Physical SocietyPhysical Review Research2643-15642023-03-015101319010.1103/PhysRevResearch.5.013190Preparing valence-bond-solid states on noisy intermediate-scale quantum computersBruno MurtaPedro M. Q. CruzJ. Fernández-RossierQuantum state preparation is a key step in all digital quantum simulation algorithms. Here we propose methods to initialize on a gate-based quantum computer a general class of quantum spin wave functions, the so-called valence-bond-solid (VBS) states, that are important for two reasons. First, VBS states are the exact ground states of a class of interacting quantum spin models introduced by Affleck, Kennedy, Lieb, and Tasaki (AKLT). Second, the two-dimensional VBS states are universal resource states for measurement-based quantum computing. We find that schemes to prepare VBS states based on their tensor-network representations yield quantum circuits that are too deep to be within reach of noisy intermediate-scale quantum (NISQ) computers. We then apply the general nondeterministic method herein proposed to the preparation of the spin-1 and spin-3/2 VBS states, the ground states of the AKLT models defined in one dimension and in the honeycomb lattice, respectively. Shallow quantum circuits of depth independent of the lattice size are explicitly derived for both cases, making use of optimization schemes that outperform standard basis gate decomposition methods. The probabilistic nature of the proposed routine translates into an average number of repetitions to successfully prepare the VBS state that scales exponentially with the number of lattice sites N. However, two strategies to quadratically reduce this repetition overhead for any bipartite lattice are devised. Our approach should permit to use NISQ processors to explore the AKLT model and variants thereof, outperforming conventional numerical methods in the near future.http://doi.org/10.1103/PhysRevResearch.5.013190
spellingShingle Bruno Murta
Pedro M. Q. Cruz
J. Fernández-Rossier
Preparing valence-bond-solid states on noisy intermediate-scale quantum computers
Physical Review Research
title Preparing valence-bond-solid states on noisy intermediate-scale quantum computers
title_full Preparing valence-bond-solid states on noisy intermediate-scale quantum computers
title_fullStr Preparing valence-bond-solid states on noisy intermediate-scale quantum computers
title_full_unstemmed Preparing valence-bond-solid states on noisy intermediate-scale quantum computers
title_short Preparing valence-bond-solid states on noisy intermediate-scale quantum computers
title_sort preparing valence bond solid states on noisy intermediate scale quantum computers
url http://doi.org/10.1103/PhysRevResearch.5.013190
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