Efficient Variational Quantum Linear Solver for Structured Sparse Matrices

Fuente: arXiv
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Main Authors: Gnanasekaran, Abeynaya, Surana, Amit
Format: Preprint
Published: 2024
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author Gnanasekaran, Abeynaya
Surana, Amit
author_facet Gnanasekaran, Abeynaya
Surana, Amit
contents We develop a novel approach for efficiently applying variational quantum linear solver (VQLS) in context of structured sparse matrices. Such matrices frequently arise during numerical solution of partial differential equations which are ubiquitous in science and engineering. Conventionally, Pauli basis is used for linear combination of unitary (LCU) decomposition of the underlying matrix to facilitate the evaluation the global/local VQLS cost functions. However, Pauli basis in worst case can result in number of LCU terms that scale quadratically with respect to the matrix size. We show that by using an alternate basis one can better exploit the sparsity and underlying structure of matrix leading to number of tensor product terms which scale only logarithmically with respect to the matrix size. Given this new basis is comprised of non-unitary operators, we employ the concept of unitary completion to design efficient quantum circuits for computing the global/local VQLS cost functions. We compare our approach with other related concepts in the literature including unitary dilation and measurement in Bell basis, and discuss its pros/cons while using VQLS applied to Heat equation as an example.
format Preprint
id arxiv_https___arxiv_org_abs_2404_16991
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Efficient Variational Quantum Linear Solver for Structured Sparse Matrices
Gnanasekaran, Abeynaya
Surana, Amit
Quantum Physics
Numerical Analysis
We develop a novel approach for efficiently applying variational quantum linear solver (VQLS) in context of structured sparse matrices. Such matrices frequently arise during numerical solution of partial differential equations which are ubiquitous in science and engineering. Conventionally, Pauli basis is used for linear combination of unitary (LCU) decomposition of the underlying matrix to facilitate the evaluation the global/local VQLS cost functions. However, Pauli basis in worst case can result in number of LCU terms that scale quadratically with respect to the matrix size. We show that by using an alternate basis one can better exploit the sparsity and underlying structure of matrix leading to number of tensor product terms which scale only logarithmically with respect to the matrix size. Given this new basis is comprised of non-unitary operators, we employ the concept of unitary completion to design efficient quantum circuits for computing the global/local VQLS cost functions. We compare our approach with other related concepts in the literature including unitary dilation and measurement in Bell basis, and discuss its pros/cons while using VQLS applied to Heat equation as an example.
title Efficient Variational Quantum Linear Solver for Structured Sparse Matrices
topic Quantum Physics
Numerical Analysis
url https://arxiv.org/abs/2404.16991