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Quantum process tomography is a critical capability for building quantum computers, enabling quantum networks, and understanding quantum sensors. Like quantum state tomography, the process tomography of an arbitrary quantum channel requires…

Quantum Physics · Physics 2023-05-26 Jonathan Kunjummen , Minh C. Tran , Daniel Carney , Jacob M. Taylor

We introduce a general statistical learning theory for processes that take as input a classical random variable and output a quantum state. Our setting is motivated by the practical situation in which one desires to learn a quantum process…

Quantum Physics · Physics 2025-02-27 Marco Fanizza , Yihui Quek , Matteo Rosati

Randomized measurement protocols such as classical shadows represent powerful resources for quantum technologies, with applications ranging from quantum state characterization and process tomography to machine learning and error mitigation.…

Quantum Physics · Physics 2024-06-18 Laurin E. Fischer , Timothée Dao , Ivano Tavernelli , Francesco Tacchino

Classical shadow tomography is a powerful randomized measurement protocol for predicting many properties of a quantum state with few measurements. Two classical shadow protocols have been extensively studied in the literature: the…

Quantum Physics · Physics 2023-06-07 Ahmed A. Akhtar , Hong-Ye Hu , Yi-Zhuang You

We investigate the advantages of using autoregressive neural quantum states as ansatze for classical shadow tomography to improve its predictive power. We introduce a novel estimator for optimizing the cross-entropy loss function using…

Quantum Physics · Physics 2024-08-23 Wirawat Kokaew , Bohdan Kulchytskyy , Shunji Matsuura , Pooya Ronagh

Estimating properties of a quantum state is an indispensable task in various applications of quantum information processing. To predict properties in the post-processing stage, it is inherent to first perceive the quantum state with a…

Quantum Physics · Physics 2024-02-29 Yinfei Li , Sanjib Ghosh , Jiangwei Shang , Qihua Xiong , Xiangdong Zhang

Tomograms are obtained as probability distributions and are used to reconstruct a quantum state from experimentally measured values. We study the evolution of tomograms for different quantum systems, both finite and infinite dimensional. In…

Quantum Physics · Physics 2022-06-10 Kishore Thapliyal , Subhashish Banerjee , Anirban Pathak

Shadow estimation provides an efficient framework for estimating observable expectation values using randomized measurements. While originally developed for discrete-variable systems, its recent extensions to continuous-variable (CV)…

Quantum Physics · Physics 2025-12-16 Ruyu Yang , Xiaoming Sun , Hongyi Zhou

We give the first tight sample complexity bounds for shadow tomography and classical shadows in the regime where the target error is below some sufficiently small inverse polynomial in the dimension of the Hilbert space. Formally we give a…

Quantum Physics · Physics 2024-07-22 Sitan Chen , Jerry Li , Allen Liu

Quantum state tomography is a fundamental tool in quantum information processing. It allows us to estimate the state of a quantum system by measuring different observables on many identically prepared copies of the system. This is, in…

Quantum Physics · Physics 2011-11-28 Carlos A. Riofrío

Properties of quantum states have disclosed new and revolutionary technologies, ranging from quantum information to quantum imaging. This last field is addressed to overcome limits of classical imaging by exploiting specific properties of…

Quantum Physics · Physics 2015-05-19 Giorgio Brida , Marco Genovese , Alice Meda , Ivano Ruo Berchera

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

Classical computation of electronic properties in large-scale materials remains challenging. Quantum computation has the potential to offer advantages in memory footprint and computational scaling. However, general and practical quantum…

Computational Physics · Physics 2025-10-14 Yiran Bai , Feng Xiong , Xueheng Kuang

We study the problem of quantum-state tomography under the assumption that the state of the system is close to pure. In this context, an efficient measurements that one typically formulates uniquely identify a pure state from within the set…

Quantum Physics · Physics 2016-05-11 Amir Kalev , Charles H. Baldwin , Ivan H. Deutsch

Quantum mechanics provides cryptographic primitives whose security is grounded in hardness assumptions independent of those underlying classical cryptography. However, existing proposals require low-noise quantum communication and…

Improving the performance of quantum algorithms is a fundamental task to achieve quantum advantage. In many cases, extracting information from quantum systems poses an important challenge for practical implementations in real-world quantum…

Quantum Physics · Physics 2025-02-28 Leticia Bertuzzi , João P. Engster , Evandro C. R. da Rosa , Eduardo I. Duzzioni

Properties of quantum states have disclosed new technologies, ranging from quantum information to quantum metrology. Among them a recent research field is quantum imaging, addressed to overcome limits of classical imaging by exploiting…

Quantum Physics · Physics 2010-04-09 G. Brida , M. Genovese , I. Ruo Berchera

Quantum sensing exploits quantum phenomena to enhance the detection and estimation of classical parameters of physical systems and biological entities, particularly so as to overcome the inefficiencies of its classical counterparts. A…

Quantum state tomography, the ability to deduce the density matrix of a quantum system from measured data, is of fundamental importance for the verification of present and future quantum devices. It has been realized in systems with few…

Quantum Physics · Physics 2010-02-22 M. Cramer , M. B. Plenio

Estimation of expectation values of incompatible observables is an essential practical task in quantum computing, especially for approximating energies of chemical and other many-body quantum systems. In this work we introduce a method for…

Quantum Physics · Physics 2023-03-14 Daniel McNulty , Filip B. Maciejewski , Michał Oszmaniec