$\mathcal{O}(n)$ alternative to Quantum Fourier Transform with efficient neural net classical post-processing

Fuente: arXiv
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Main Authors: Bian, Kaiming, Wen, Zujin, Dahlsten, Oscar
Format: Preprint
Published: 2026
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author Bian, Kaiming
Wen, Zujin
Dahlsten, Oscar
author_facet Bian, Kaiming
Wen, Zujin
Dahlsten, Oscar
contents The Quantum Fourier Transform (QFT) is required by hidden subgroup problem (HSP) algorithms, including Shor's algorithm for factoring. The circuit depth of the QFT remains challenging for near-term hardware. To find shallower alternatives we identify two properties that are exploited by the QFT to enable HSP. Firstly, the shift invariance of the QFT allows for the removal of a random overall shift. Secondly, the QFT retains information about the hidden subgroup generator accessible in the measurement outcomes. We quantify that information via the discrete Fisher information. We construct a family of shallow circuits using Hadamards and controlled-Phase gates, HP-$L$ circuits, that we prove preserve shift invariance. Numerical analysis shows these circuits retain exponentially growing Fisher information. The $\mathcal{O}(n)$ HP-$1$ can replace the $\mathcal{O}(n^2)$ QFT in Shor's algorithm, as demonstrated numerically, with an efficient neural network implementing classical post-processing.
format Preprint
id arxiv_https___arxiv_org_abs_2605_16998
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle $\mathcal{O}(n)$ alternative to Quantum Fourier Transform with efficient neural net classical post-processing
Bian, Kaiming
Wen, Zujin
Dahlsten, Oscar
Quantum Physics
Machine Learning
The Quantum Fourier Transform (QFT) is required by hidden subgroup problem (HSP) algorithms, including Shor's algorithm for factoring. The circuit depth of the QFT remains challenging for near-term hardware. To find shallower alternatives we identify two properties that are exploited by the QFT to enable HSP. Firstly, the shift invariance of the QFT allows for the removal of a random overall shift. Secondly, the QFT retains information about the hidden subgroup generator accessible in the measurement outcomes. We quantify that information via the discrete Fisher information. We construct a family of shallow circuits using Hadamards and controlled-Phase gates, HP-$L$ circuits, that we prove preserve shift invariance. Numerical analysis shows these circuits retain exponentially growing Fisher information. The $\mathcal{O}(n)$ HP-$1$ can replace the $\mathcal{O}(n^2)$ QFT in Shor's algorithm, as demonstrated numerically, with an efficient neural network implementing classical post-processing.
title $\mathcal{O}(n)$ alternative to Quantum Fourier Transform with efficient neural net classical post-processing
topic Quantum Physics
Machine Learning
url https://arxiv.org/abs/2605.16998