An Exponential Separation Between Quantum and Quantum-Inspired Classical Algorithms for Linear Systems

Fuente: arXiv
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Main Authors: Grønlund, Allan, Larsen, Kasper Green
Format: Preprint
Published: 2024
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author Grønlund, Allan
Larsen, Kasper Green
author_facet Grønlund, Allan
Larsen, Kasper Green
contents Achieving a provable exponential quantum speedup for an important machine learning task has been a central research goal since the seminal HHL quantum algorithm for solving linear systems and the subsequent quantum recommender systems algorithm by Kerenidis and Prakash. These algorithms were initially believed to be strong candidates for exponential speedups, but a lower bound ruling out similar classical improvements remained absent. In breakthrough work by Tang, it was demonstrated that this lack of progress in classical lower bounds was for good reasons. Concretely, she gave a classical counterpart of the quantum recommender systems algorithm, reducing the quantum advantage to a mere polynomial. Her approach is quite general and was named quantum-inspired classical algorithms. Since then, almost all the initially exponential quantum machine learning speedups have been reduced to polynomial via new quantum-inspired classical algorithms. From the current state-of-affairs, it is unclear whether we can hope for exponential quantum speedups for any natural machine learning task. In this work, we present the first such provable exponential separation between quantum and quantum-inspired classical algorithms for the basic problem of solving a linear system when the input matrix is well-conditioned and has sparse rows and columns.
format Preprint
id arxiv_https___arxiv_org_abs_2411_02087
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle An Exponential Separation Between Quantum and Quantum-Inspired Classical Algorithms for Linear Systems
Grønlund, Allan
Larsen, Kasper Green
Quantum Physics
Computational Complexity
Data Structures and Algorithms
Machine Learning
Achieving a provable exponential quantum speedup for an important machine learning task has been a central research goal since the seminal HHL quantum algorithm for solving linear systems and the subsequent quantum recommender systems algorithm by Kerenidis and Prakash. These algorithms were initially believed to be strong candidates for exponential speedups, but a lower bound ruling out similar classical improvements remained absent. In breakthrough work by Tang, it was demonstrated that this lack of progress in classical lower bounds was for good reasons. Concretely, she gave a classical counterpart of the quantum recommender systems algorithm, reducing the quantum advantage to a mere polynomial. Her approach is quite general and was named quantum-inspired classical algorithms. Since then, almost all the initially exponential quantum machine learning speedups have been reduced to polynomial via new quantum-inspired classical algorithms. From the current state-of-affairs, it is unclear whether we can hope for exponential quantum speedups for any natural machine learning task. In this work, we present the first such provable exponential separation between quantum and quantum-inspired classical algorithms for the basic problem of solving a linear system when the input matrix is well-conditioned and has sparse rows and columns.
title An Exponential Separation Between Quantum and Quantum-Inspired Classical Algorithms for Linear Systems
topic Quantum Physics
Computational Complexity
Data Structures and Algorithms
Machine Learning
url https://arxiv.org/abs/2411.02087