Worst-case Harrow-Hassidim-Lloyd algorithm with average-case correct quantum Fourier transform
Quantum Physics
2026-04-14 v1
Abstract
In [\href{https://quantum-journal.org/papers/q-2022-12-07-872/}{Quantum 6, 872, 2022}], Linden and de Wolf proposed a lightweight protocol for verifying the average-case correct behavior of the quantum Fourier transform (QFT). They proved that good average-case QFT performance suffices for good worst-case performance in several quantum tasks. Here we provide another application of this worst-case-to-average-case reduction, using a strengthened Linden-de Wolf protocol. We show that, across three distinct scenarios, the Harrow-Hassidim-Lloyd algorithm can be executed with provably good worst-case performance, assuming only that the QFT is correct on average.
Cite
@article{arxiv.2604.10428,
title = {Worst-case Harrow-Hassidim-Lloyd algorithm with average-case correct quantum Fourier transform},
author = {Changpeng Shao},
journal= {arXiv preprint arXiv:2604.10428},
year = {2026}
}
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23 pages