Biased Estimator Channels for Classical Shadows

Fuente: arXiv
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Auteurs principaux: Cai, Zhenyu, Chapman, Adrian, Jnane, Hamza, Koczor, Bálint
Format: Preprint
Publié: 2024
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author Cai, Zhenyu
Chapman, Adrian
Jnane, Hamza
Koczor, Bálint
author_facet Cai, Zhenyu
Chapman, Adrian
Jnane, Hamza
Koczor, Bálint
contents Extracting classical information from quantum systems is of fundamental importance, and classical shadows allow us to extract a large amount of information using relatively few measurements. Conventional shadow estimators are unbiased and thus approach the true mean in the infinite-sample limit. In this work, we consider a biased scheme, intentionally introducing a bias by rescaling the conventional classical shadows estimators can reduce the error in the finite-sample regime. The approach is straightforward to implement and requires no quantum resources. We analytically prove average case as well as worst- and best-case scenarios, and rigorously prove that it is, in principle, always worth biasing the estimators. We illustrate our approach in a quantum simulation task of a $12$-qubit spin-ring problem and demonstrate how estimating expected values of non-local perturbations can be significantly more efficient using our biased scheme.
format Preprint
id arxiv_https___arxiv_org_abs_2402_09511
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Biased Estimator Channels for Classical Shadows
Cai, Zhenyu
Chapman, Adrian
Jnane, Hamza
Koczor, Bálint
Quantum Physics
Extracting classical information from quantum systems is of fundamental importance, and classical shadows allow us to extract a large amount of information using relatively few measurements. Conventional shadow estimators are unbiased and thus approach the true mean in the infinite-sample limit. In this work, we consider a biased scheme, intentionally introducing a bias by rescaling the conventional classical shadows estimators can reduce the error in the finite-sample regime. The approach is straightforward to implement and requires no quantum resources. We analytically prove average case as well as worst- and best-case scenarios, and rigorously prove that it is, in principle, always worth biasing the estimators. We illustrate our approach in a quantum simulation task of a $12$-qubit spin-ring problem and demonstrate how estimating expected values of non-local perturbations can be significantly more efficient using our biased scheme.
title Biased Estimator Channels for Classical Shadows
topic Quantum Physics
url https://arxiv.org/abs/2402.09511