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Auteurs principaux: Karaiskos, Georgios, Rudolph, Dorian, Meyer, Johannes Jakob, Eisert, Jens, Gharibian, Sevag
Format: Preprint
Publié: 2025
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Accès en ligne:https://arxiv.org/abs/2510.08515
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author Karaiskos, Georgios
Rudolph, Dorian
Meyer, Johannes Jakob
Eisert, Jens
Gharibian, Sevag
author_facet Karaiskos, Georgios
Rudolph, Dorian
Meyer, Johannes Jakob
Eisert, Jens
Gharibian, Sevag
contents Classical shadows are succinct classical representations of quantum states which allow one to encode a set of properties P of a quantum state rho, while only requiring measurements on logarithmically many copies of rho in the size of P. In this work, we initiate the study of verification of classical shadows, denoted classical shadow validity (CSV), from the perspective of computational complexity, which asks: Given a classical shadow S, how hard is it to verify that S predicts the measurement statistics of a quantum state? We first show that even for the elegantly simple classical shadow protocol of [Huang, Kueng, Preskill, Nature Physics 2020] utilizing local Clifford measurements, CSV is QMA-complete. This hardness continues to hold for the high-dimensional extension of said protocol due to [Mao, Yi, and Zhu, PRL 2025]. In contrast, we show that for the HKP and MYZ protocols utilizing global Clifford measurements, CSV can be "dequantized" for low-Frobenius norm observables, i.e., solved in randomized poly-time with standard sampling assumptions. Among other results, we also show that CSV for exponentially many observables is complete for a quantum generalization of the second level of the polynomial hierarchy, yielding the first natural complete problem for such a class.
format Preprint
id arxiv_https___arxiv_org_abs_2510_08515
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle How hard is it to verify a classical shadow?
Karaiskos, Georgios
Rudolph, Dorian
Meyer, Johannes Jakob
Eisert, Jens
Gharibian, Sevag
Quantum Physics
Computational Complexity
Classical shadows are succinct classical representations of quantum states which allow one to encode a set of properties P of a quantum state rho, while only requiring measurements on logarithmically many copies of rho in the size of P. In this work, we initiate the study of verification of classical shadows, denoted classical shadow validity (CSV), from the perspective of computational complexity, which asks: Given a classical shadow S, how hard is it to verify that S predicts the measurement statistics of a quantum state? We first show that even for the elegantly simple classical shadow protocol of [Huang, Kueng, Preskill, Nature Physics 2020] utilizing local Clifford measurements, CSV is QMA-complete. This hardness continues to hold for the high-dimensional extension of said protocol due to [Mao, Yi, and Zhu, PRL 2025]. In contrast, we show that for the HKP and MYZ protocols utilizing global Clifford measurements, CSV can be "dequantized" for low-Frobenius norm observables, i.e., solved in randomized poly-time with standard sampling assumptions. Among other results, we also show that CSV for exponentially many observables is complete for a quantum generalization of the second level of the polynomial hierarchy, yielding the first natural complete problem for such a class.
title How hard is it to verify a classical shadow?
topic Quantum Physics
Computational Complexity
url https://arxiv.org/abs/2510.08515