Constant Factor Analysis of Optimal Quantum Linear Solvers in Practice

Fuente: arXiv
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Auteurs principaux: Costa, Pedro C. S., Dalzell, Alexander M., An, Dong, Berry, Dominic W.
Format: Preprint
Publié: 2026
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author Costa, Pedro C. S.
Dalzell, Alexander M.
An, Dong
Berry, Dominic W.
author_facet Costa, Pedro C. S.
Dalzell, Alexander M.
An, Dong
Berry, Dominic W.
contents Optimal quantum linear equation solvers provide complexity $O(κ\log(1/ε))$, where $κ$ is the condition number and $ε$ is the allowable error. The optimal solver using a discrete adiabatic approach [PRX Quantum 3, 040303 (2022)] has large analytically proven constant factors for the upper bound on the complexity. The constant factors were later found to be about 1,200 times smaller in numerical testing [Quantum 9, 1887 (2025)]. This meant it is about an order of magnitude more efficient than using a randomised approach from [PRX Quantum 6, 040373 (2025)], which has far smaller analytically proven constant factors. Recently, a ``Shortcut'' method has been found to provide an optimal solver which also has small proven constant factors. In the present work, we conduct a comprehensive numerical analysis comparing this method with the adiabatic solver for two families of random linear systems. We find that, in the case where the solution norm is unknown, the adiabatic solver provides slightly better performance. If the solution norm is known, then the shortcut method provides significantly better performance for non-Hermitian matrices.
format Preprint
id arxiv_https___arxiv_org_abs_2604_22185
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Constant Factor Analysis of Optimal Quantum Linear Solvers in Practice
Costa, Pedro C. S.
Dalzell, Alexander M.
An, Dong
Berry, Dominic W.
Quantum Physics
Optimal quantum linear equation solvers provide complexity $O(κ\log(1/ε))$, where $κ$ is the condition number and $ε$ is the allowable error. The optimal solver using a discrete adiabatic approach [PRX Quantum 3, 040303 (2022)] has large analytically proven constant factors for the upper bound on the complexity. The constant factors were later found to be about 1,200 times smaller in numerical testing [Quantum 9, 1887 (2025)]. This meant it is about an order of magnitude more efficient than using a randomised approach from [PRX Quantum 6, 040373 (2025)], which has far smaller analytically proven constant factors. Recently, a ``Shortcut'' method has been found to provide an optimal solver which also has small proven constant factors. In the present work, we conduct a comprehensive numerical analysis comparing this method with the adiabatic solver for two families of random linear systems. We find that, in the case where the solution norm is unknown, the adiabatic solver provides slightly better performance. If the solution norm is known, then the shortcut method provides significantly better performance for non-Hermitian matrices.
title Constant Factor Analysis of Optimal Quantum Linear Solvers in Practice
topic Quantum Physics
url https://arxiv.org/abs/2604.22185