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We consider 1-qubit mixed quantum state estimation by adaptively updating measurements according to previously obtained outcomes and measurement settings. Updates are determined by the average-variance-optimality (A-optimality) criterion,…

Quantum Physics · Physics 2012-05-21 Takanori Sugiyama , Peter S. Turner , Mio Murao

Quantum hardware suffers from intrinsic device heterogeneity and environmental drift, forcing practitioners to choose between suboptimal non-adaptive controllers or costly per-device recalibration. We derive a scaling law lower bound for…

Machine Learning · Computer Science 2026-05-21 Nima Leclerc , Chris Miller , Nicholas Brawand

Recently, tremendous progress has been made in the field of quantum science and technologies: different platforms for quantum simulation as well as quantum computing, ranging from superconducting qubits to neutral atoms, are starting to…

Fingerprinting arguments, first introduced by Bun, Ullman, and Vadhan (STOC 2014), are the most widely used method for establishing lower bounds on the sample complexity or error of approximately differentially private (DP) algorithms.…

Cryptography and Security · Computer Science 2024-07-08 Naty Peter , Eliad Tsfadia , Jonathan Ullman

We study the relative error of the state-dependent N=>L cloning. A copying transformation and dimension of state space are not specified. Only the unitarity of quantum mechanical transformations is used. The proposed approach is based on…

Quantum Physics · Physics 2007-05-23 A. E. Rastegin

Estimation of quantum states and measurements is crucial for the implementation of quantum information protocols. The standard method for each is quantum tomography. However, quantum tomography suffers from systematic errors caused by…

Quantum Physics · Physics 2018-10-19 Adam C. Keith , Charles H. Baldwin , Scott Glancy , E. Knill

In quantum information transformation and quantum computation, the most critical issues are security and accuracy. These features, therefore, stimulate research on quantum state characterization. A characterization tool, Quantum state…

Quantum Physics · Physics 2023-06-01 Xudan Chai , Teng Ma , Qihao Guo , Zhangqi Yin , Hao Wu , Qing Zhao

How well can multiple incompatible observables be implemented by a single measurement? This is a fundamental problem in quantum mechanics with wide implications for the performance optimization of numerous tasks in quantum information…

Quantum Physics · Physics 2024-10-10 Hongzhen Chen , Lingna Wang , Haidong Yuan

Learning about physical systems from quantum-enhanced experiments, relying on a quantum memory and quantum processing, can outperform learning from experiments in which only classical memory and processing are available. Whereas quantum…

Quantum Physics · Physics 2024-06-21 Matthias C. Caro

We prove the expected disturbance caused to a quantum system by a sequence of randomly ordered two-outcome projective measurements is upper bounded by the square root of the probability that at least one measurement in the sequence accepts.…

Quantum Physics · Physics 2024-03-12 Adam Bene Watts , John Bostanci

In this work, we initiate the study of learning quantum processes from quantum statistical queries. We focus on two fundamental learning tasks in this new access model: shadow tomography of quantum processes and process tomography with…

Quantum Physics · Physics 2025-05-14 Chirag Wadhwa , Mina Doosti

Quantum measurements are not deterministic. For this reason quantum measurements are repeated for a number of shots on identically prepared systems. The uncertainty in each measurement depends on the number of shots and the expected outcome…

Quantum Physics · Physics 2025-03-12 Pieter Thijs Eendebak

Quantum detector tomography is a fundamental technique for calibrating quantum devices and performing quantum engineering tasks. In this paper, we design optimal probe states for detector estimation based on the minimum upper bound of the…

Quantum Physics · Physics 2022-01-13 Shuixin Xiao , Yuanlong Wang , Daoyi Dong , Jun Zhang

We revisit the problem of estimating an unknown parameter of a pure quantum state, and investigate `null-measurement' strategies in which the experimenter aims to measure in a basis that contains a vector close to the true system state.…

Quantum Physics · Physics 2023-10-11 Federico Girotti , Alfred Godley , Mădălin Guţă

Intuitively, if a density operator has small rank, then it should be easier to estimate from experimental data, since in this case only a few eigenvectors need to be learned. We prove two complementary results that confirm this intuition.…

Quantum Physics · Physics 2012-10-18 Steven T. Flammia , David Gross , Yi-Kai Liu , Jens Eisert

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

Quantum sensing harnesses the unique properties of quantum systems to enable precision measurements of physical quantities such as time, magnetic and electric fields, acceleration, and gravitational gradients well beyond the limits of…

Quantum Physics · Physics 2025-07-23 Ivana Nikoloska , Ruud Van Sloun , Osvaldo Simeone

High-dimensional quantum information processing has become a mature field of research with several different approaches being adopted for the encoding of $D$-dimensional quantum systems. Such progress has fueled the search of reliable…

Quantum Physics · Physics 2019-01-30 D. Martínez , M. A. Solís-Prosser , G. Cañas , O. Jiménez , A. Delgado , G. Lima

We use a meta-learning neural-network approach to analyse data from a measured quantum state. Once our neural network has been trained it can be used to efficiently sample measurements of the state in measurement bases not contained in the…

Quantum Physics · Physics 2021-07-01 Alistair W. R. Smith , Johnnie Gray , M. S. Kim

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