A quantum linear system algorithm for dense matrices

Solving linear systems of equations is a frequently encountered problem in machine learning and optimisation. Given a matrix \(A\) and a vector \(\mathbf b\) the task is to find the vector \(\mathbf x\) such that \(A \mathbf x = \mathbf b\). We describe a quantum algorithm that achieves a sparsity-i...

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Vydané v:arXiv.org
Hlavní autori: Wossnig, Leonard, Zhao, Zhikuan, Prakash, Anupam
Médium: Paper
Jazyk:English
Vydavateľské údaje: Ithaca Cornell University Library, arXiv.org 03.05.2017
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ISSN:2331-8422
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Shrnutí:Solving linear systems of equations is a frequently encountered problem in machine learning and optimisation. Given a matrix \(A\) and a vector \(\mathbf b\) the task is to find the vector \(\mathbf x\) such that \(A \mathbf x = \mathbf b\). We describe a quantum algorithm that achieves a sparsity-independent runtime scaling of \(\mathcal{O}(\kappa^2 \|A\|_F \text{polylog}(n)/\epsilon)\), where \(n\times n\) is the dimensionality of \(A\) with Frobenius norm \(\|A\|_F\), \(\kappa\) denotes the condition number of \(A\), and \(\epsilon\) is the desired precision parameter. When applied to a dense matrix with spectral norm bounded by a constant, the runtime of the proposed algorithm is bounded by \(\mathcal{O}(\kappa^2\sqrt{n} \text{polylog}(n)/\epsilon)\), which is a quadratic improvement over known quantum linear system algorithms. Our algorithm is built upon a singular value estimation subroutine, which makes use of a memory architecture that allows for efficient preparation of quantum states that correspond to the rows and row Frobenius norms of \(A\).
Bibliografia:SourceType-Working Papers-1
ObjectType-Working Paper/Pre-Print-1
content type line 50
ISSN:2331-8422
DOI:10.48550/arxiv.1704.06174