Quantum Advantage in Learning Mixed Unitary Channels

Fuente: arXiv
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Hauptverfasser: Tu, Yue, Jiang, Liang
Format: Preprint
Veröffentlicht: 2025
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author Tu, Yue
Jiang, Liang
author_facet Tu, Yue
Jiang, Liang
contents We study the task of learning mixed unitary channels using Fisher information, under different quantum resource assumptions including ancilla and concatenation. Our result shows that the asymptotic sample complexity scales as $\frac{r}{d\varepsilon^2}$, where $r$ is the rank of the channel (i.e.\ the number of different unitaries), $d$ is the dimension of the system, and $\varepsilon^2$ is the mean-square error. Thus the critical resource is the ancilla, which mirrors the result in~\cite{chen2022quantum} but in a more precise form, as we point out that $r$ is also important. Additionally, we demonstrate the practical potential of mixed unitary channels by showing that random mixed unitary channels are easy to learn.
format Preprint
id arxiv_https___arxiv_org_abs_2511_13683
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Quantum Advantage in Learning Mixed Unitary Channels
Tu, Yue
Jiang, Liang
Quantum Physics
Mathematical Physics
We study the task of learning mixed unitary channels using Fisher information, under different quantum resource assumptions including ancilla and concatenation. Our result shows that the asymptotic sample complexity scales as $\frac{r}{d\varepsilon^2}$, where $r$ is the rank of the channel (i.e.\ the number of different unitaries), $d$ is the dimension of the system, and $\varepsilon^2$ is the mean-square error. Thus the critical resource is the ancilla, which mirrors the result in~\cite{chen2022quantum} but in a more precise form, as we point out that $r$ is also important. Additionally, we demonstrate the practical potential of mixed unitary channels by showing that random mixed unitary channels are easy to learn.
title Quantum Advantage in Learning Mixed Unitary Channels
topic Quantum Physics
Mathematical Physics
url https://arxiv.org/abs/2511.13683