Solving the encoding bottleneck: of the HHL algorithm, by the HHL algorithm

Fuente: arXiv
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Autore principale: He, Guang Ping
Natura: Preprint
Pubblicazione: 2025
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author He, Guang Ping
author_facet He, Guang Ping
contents The Harrow-Hassidim-Lloyd (HHL) algorithm offers exponential speedup for solving the quantum linear-system problem. But some caveats for the speedup could be hard to met. One of the difficulties is the encoding bottleneck, i.e., the efficient preparation of the initial quantum state. To prepare an arbitrary $N$-dimensional state exactly, existing state-preparation approaches generally require a runtime of $O(N)$, which will ruin the speedup of the HHL algorithm. Here we show that the states can be prepared approximately with a runtime of $O(poly(\log N))$ by employing a slightly modified version of the HHL algorithm itself. Thus, applying this approach to prepare the initial state of the original HHL algorithm can preserve the exponential speedup advantage. It can also serve as a standalone solution for other applications demanding fast state preparation.
format Preprint
id arxiv_https___arxiv_org_abs_2502_13534
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Solving the encoding bottleneck: of the HHL algorithm, by the HHL algorithm
He, Guang Ping
Quantum Physics
Artificial Intelligence
Machine Learning
The Harrow-Hassidim-Lloyd (HHL) algorithm offers exponential speedup for solving the quantum linear-system problem. But some caveats for the speedup could be hard to met. One of the difficulties is the encoding bottleneck, i.e., the efficient preparation of the initial quantum state. To prepare an arbitrary $N$-dimensional state exactly, existing state-preparation approaches generally require a runtime of $O(N)$, which will ruin the speedup of the HHL algorithm. Here we show that the states can be prepared approximately with a runtime of $O(poly(\log N))$ by employing a slightly modified version of the HHL algorithm itself. Thus, applying this approach to prepare the initial state of the original HHL algorithm can preserve the exponential speedup advantage. It can also serve as a standalone solution for other applications demanding fast state preparation.
title Solving the encoding bottleneck: of the HHL algorithm, by the HHL algorithm
topic Quantum Physics
Artificial Intelligence
Machine Learning
url https://arxiv.org/abs/2502.13534