Phase shadow: A noise-tolerant path to global quantum property estimation

Fuente: arXiv
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Auteurs principaux: Zhang, Qingyue, Qin, Dayue, You, Zhou, Xu, Feng, Eisert, Jens, Zhou, You
Format: Preprint
Publié: 2025
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author Zhang, Qingyue
Qin, Dayue
You, Zhou
Xu, Feng
Eisert, Jens
Zhou, You
author_facet Zhang, Qingyue
Qin, Dayue
You, Zhou
Xu, Feng
Eisert, Jens
Zhou, You
contents Measuring global quantum properties-such as the fidelity to complex multipartite states-is both an essential and experimentally challenging task. Classical shadow estimation offers favorable sample complexity, but typically relies on many-qubit circuits that are difficult to realize on current platforms. We propose the robust phase shadow scheme, a measurement framework based on random circuits with controlled-$Z$ as the unique entangling gate type, tailored to architectures such as trapped ions and neutral atoms. Leveraging tensor diagrammatic reasoning, we rigorously analyze the induced circuit ensemble and show that phase shadows match the performance of full Clifford-based ones. Importantly, our approach supports a noise-robust extension via purely classical post-processing, enabling reliable estimation under gate-dependent noise where existing techniques often fail. Additionally, by exploiting structural properties of random stabilizer states, we design an efficient post-processing algorithm that resolves a key computational bottleneck in previous shadow protocols. Our results enhance the practicality of shadow-based techniques, providing a robust and scalable route for estimating global properties in noisy quantum systems.
format Preprint
id arxiv_https___arxiv_org_abs_2507_13237
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Phase shadow: A noise-tolerant path to global quantum property estimation
Zhang, Qingyue
Qin, Dayue
You, Zhou
Xu, Feng
Eisert, Jens
Zhou, You
Quantum Physics
Measuring global quantum properties-such as the fidelity to complex multipartite states-is both an essential and experimentally challenging task. Classical shadow estimation offers favorable sample complexity, but typically relies on many-qubit circuits that are difficult to realize on current platforms. We propose the robust phase shadow scheme, a measurement framework based on random circuits with controlled-$Z$ as the unique entangling gate type, tailored to architectures such as trapped ions and neutral atoms. Leveraging tensor diagrammatic reasoning, we rigorously analyze the induced circuit ensemble and show that phase shadows match the performance of full Clifford-based ones. Importantly, our approach supports a noise-robust extension via purely classical post-processing, enabling reliable estimation under gate-dependent noise where existing techniques often fail. Additionally, by exploiting structural properties of random stabilizer states, we design an efficient post-processing algorithm that resolves a key computational bottleneck in previous shadow protocols. Our results enhance the practicality of shadow-based techniques, providing a robust and scalable route for estimating global properties in noisy quantum systems.
title Phase shadow: A noise-tolerant path to global quantum property estimation
topic Quantum Physics
url https://arxiv.org/abs/2507.13237