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We introduce "holographic shadows", a new class of randomized measurement schemes for classical shadow tomography that achieves the optimal scaling of sample complexity for learning geometrically local Pauli operators at any length scale,…

Quantum Physics · Physics 2025-12-30 Shuhan Zhang , Xiaozhou Feng , Matteo Ippoliti , Yi-Zhuang You

One of the central issues in the hidden subgroup problem is to bound the sample complexity, i.e., the number of identical samples of coset states sufficient and necessary to solve the problem. In this paper, we present general bounds for…

Quantum Physics · Physics 2008-04-26 Masahito Hayashi , Akinori Kawachi , Hirotada Kobayashi

We consider the classic question of state tomography: given copies of an unknown quantum state $\rho\in\mathbb{C}^{d\times d}$, output $\widehat{\rho}$ which is close to $\rho$ in some sense, e.g. trace distance or fidelity. When one is…

Quantum Physics · Physics 2023-05-31 Sitan Chen , Brice Huang , Jerry Li , Allen Liu , Mark Sellke

Advances in quantum technology require scalable techniques to efficiently extract information from a quantum system, such as expectation values of observables or its entropy. Traditional tomography is limited to a handful of qubits and…

Quantum Physics · Physics 2022-11-29 H. Chau Nguyen , Jan Lennart Bönsel , Jonathan Steinberg , Otfried Gühne

We revisit the basic problem of quantum state certification: given copies of unknown mixed state $\rho\in\mathbb{C}^{d\times d}$ and the description of a mixed state $\sigma$, decide whether $\sigma = \rho$ or $\|\sigma -…

Quantum Physics · Physics 2021-11-12 Sitan Chen , Jerry Li , Ryan O'Donnell

It is a fundamental problem to decide how many copies of an unknown mixed quantum state are necessary and sufficient to determine the state. Previously, it was known only that estimating states to error $\epsilon$ in trace distance required…

Quantum Physics · Physics 2017-09-01 Jeongwan Haah , Aram W. Harrow , Zhengfeng Ji , Xiaodi Wu , Nengkun Yu

Given many copies of an unknown quantum state $\rho$, we consider the task of learning a classical description of its principal eigenstate. Namely, assuming that $\rho$ has an eigenstate $|\phi\rangle$ with (unknown) eigenvalue $\lambda >…

Quantum Physics · Physics 2024-07-09 Daniel Grier , Hakop Pashayan , Luke Schaeffer

Efficiently learning expectation values of a quantum state using classical shadow tomography has become a fundamental task in quantum information theory. In a classical shadows protocol, one measures a state in a chosen basis W after it has…

Quantum Physics · Physics 2025-06-04 Maxwell West , Antonio Anna Mele , Martin Larocca , M. Cerezo

We consider the task of quantum state certification: given a description of a hypothesis state $\sigma$ and multiple copies of an unknown state $\rho$, a tester aims to determine whether the two states are equal or $\epsilon$-far in trace…

Quantum Physics · Physics 2025-07-09 Ryan O'Donnell , Chirag Wadhwa

Full quantum tomography of high-dimensional quantum systems is experimentally infeasible due to the exponential scaling of the number of required measurements on the number of qubits in the system. However, several ideas were proposed…

Quantum Physics · Physics 2021-01-20 G. I. Struchalin , Ya. A. Zagorovskii , E. V. Kovlakov , S. S. Straupe , S. P. Kulik

Pauli Measurements are the most important measurements in both theoretical and experimental aspects of quantum information science. In this paper, we explore the power of Pauli measurements in the state tomography related problems. Firstly,…

Quantum Physics · Physics 2020-09-15 Nengkun Yu

We generalize the classical shadow tomography scheme to a broad class of finite-depth or finite-time local unitary ensembles, known as locally scrambled quantum dynamics, where the unitary ensemble is invariant under local basis…

Quantum Physics · Physics 2025-10-27 Hong-Ye Hu , Soonwon Choi , Yi-Zhuang You

Quantum state tomography is a fundamental task in quantum information science, enabling detailed characterization of correlations, entanglement, and electronic structure in quantum systems. However, its exponential measurement and…

Classical shadow tomography has become a powerful tool in learning about quantum states prepared on a quantum computer. Recent works have used classical shadows to variationally enforce N-representability conditions on the 2-particle…

In recent years there has been significant interest in understanding the statistical complexity of learning from quantum data under the constraint that one can only make unentangled measurements. While a key challenge in establishing tight…

Quantum Physics · Physics 2024-12-30 Sitan Chen , Weiyuan Gong , Zhihan Zhang

We develop a classical shadow tomography protocol utilizing the randomized measurement scheme based on hybrid quantum circuits, which consist of layers of two-qubit random unitary gates mixed with single-qubit random projective…

Quantum Physics · Physics 2023-09-26 Ahmed A. Akhtar , Hong-Ye Hu , Yi-Zhuang You

In the quantum state tomography problem, one wishes to estimate an unknown $d$-dimensional mixed quantum state $\rho$, given few copies. We show that $O(d/\epsilon)$ copies suffice to obtain an estimate $\hat{\rho}$ that satisfies…

Quantum Physics · Physics 2015-09-15 Ryan O'Donnell , John Wright

Accurately estimating expectation values of quantum observables with as few measurements as possible is crucial to many quantum computing applications. We introduce a framework that covers many of existing measurement strategies and…

Measuring properties of quantum systems is a fundamental problem in quantum mechanics. We provide a simple method for estimating the expectation value of observables with an unknown quantum state. The idea is to use a data structure to…

Quantum Physics · Physics 2024-03-25 Naixu Guo , Feng Pan , Patrick Rebentrost

We provide practical and powerful schemes for learning many properties of an unknown n-qubit quantum state using a sparing number of copies of the state. Specifically, we present a depth-modulated randomized measurement scheme that…