Criteria for unbiased estimation: applications to noise-agnostic sensing and learnability of quantum channel

Fuente: arXiv
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Autores principales: Kwon, Hyukgun, Tsubouchi, Kento, Chu, Chia-Tung, Jiang, Liang
Formato: Preprint
Publicado: 2025
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author Kwon, Hyukgun
Tsubouchi, Kento
Chu, Chia-Tung
Jiang, Liang
author_facet Kwon, Hyukgun
Tsubouchi, Kento
Chu, Chia-Tung
Jiang, Liang
contents We establish the necessary and sufficient conditions for unbiased estimation in multi-parameter estimation tasks. More specifically, we first consider quantum state estimation, where multiple parameters are encoded in a quantum state, and derive simple and intuitive necessary and sufficient conditions for an unbiased estimation based on the derivatives of the encoded state. To demonstrate the utility of our framework, we consider phase estimation under unknown Pauli noise. We show that while unbiased phase estimation is infeasible with a naive scheme, employing an entangled probe with a noiseless ancilla enables unbiased estimation. Next, we extend our analysis to quantum channel estimation (equivalently, quantum channel learning), where the goal is to estimate parameters characterizing an unknown quantum channel. We establish the necessary and sufficient condition for unbiased estimation of these parameters. Notably, by interpreting unbiased estimation as learnability, our result extends to the fundamental learnability of parameters in general quantum channels. As a concrete application, we investigate the learnability of noise affecting non-Clifford gates via cycle benchmarking.
format Preprint
id arxiv_https___arxiv_org_abs_2503_17362
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Criteria for unbiased estimation: applications to noise-agnostic sensing and learnability of quantum channel
Kwon, Hyukgun
Tsubouchi, Kento
Chu, Chia-Tung
Jiang, Liang
Quantum Physics
We establish the necessary and sufficient conditions for unbiased estimation in multi-parameter estimation tasks. More specifically, we first consider quantum state estimation, where multiple parameters are encoded in a quantum state, and derive simple and intuitive necessary and sufficient conditions for an unbiased estimation based on the derivatives of the encoded state. To demonstrate the utility of our framework, we consider phase estimation under unknown Pauli noise. We show that while unbiased phase estimation is infeasible with a naive scheme, employing an entangled probe with a noiseless ancilla enables unbiased estimation. Next, we extend our analysis to quantum channel estimation (equivalently, quantum channel learning), where the goal is to estimate parameters characterizing an unknown quantum channel. We establish the necessary and sufficient condition for unbiased estimation of these parameters. Notably, by interpreting unbiased estimation as learnability, our result extends to the fundamental learnability of parameters in general quantum channels. As a concrete application, we investigate the learnability of noise affecting non-Clifford gates via cycle benchmarking.
title Criteria for unbiased estimation: applications to noise-agnostic sensing and learnability of quantum channel
topic Quantum Physics
url https://arxiv.org/abs/2503.17362