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The quantum multiparameter estimation is very different from the classical multiparameter estimation due to Heisenberg's uncertainty principle in quantum mechanics. When the optimal measurements for different parameters are incompatible,…

Quantum Physics · Physics 2021-03-31 Xiao-Ming Lu , Xiaoguang Wang

We derive lower bounds on the variance of estimators in quantum metrology by choosing test observables that define constraints on the unbiasedness of the estimator. The quantum bounds are obtained by analytical optimization over all…

Quantum Physics · Physics 2023-07-27 M. Gessner , A. Smerzi

In this paper, we consider signals with a low-rank covariance matrix which reside in a low-dimensional subspace and can be written in terms of a finite (small) number of parameters. Although such signals do not necessarily have a sparse…

Statistics Theory · Mathematics 2023-07-19 Mahdi Shaghaghi , Sergiy A. Vorobyov

The reflected entropy $S_R(A:B)$ of a density matrix $\rho_{AB}$ is a bipartite correlation measure lower-bounded by the quantum mutual information $I(A:B)$. In holographic states satisfying the quantum extremal surface formula, where the…

High Energy Physics - Theory · Physics 2021-10-12 Patrick Hayden , Onkar Parrikar , Jonathan Sorce

Estimation of local quantum fields is a crucial aspect of quantum metrology applications, and often also forms the test-bed to analyze the utility of quantum resources, like entanglement. However, so far, this has been analyzed using the…

Quantum Physics · Physics 2025-02-26 Aparajita Bhattacharyya , Ujjwal Sen

Given a large number N of copies of a qubit state of which we wish to estimate its purity, we prove that separable-measurement protocols can be as efficient as the optimal joint-measurement one if classical communication is used. This shows…

Quantum Physics · Physics 2015-06-26 E. Bagan , M. A. Ballester , R. Munoz-Tapia , O. Romero-Isart

Quantum effects like entanglement and coherent amplification can be used to drastically enhance the accuracy of quantum parameter estimation beyond classical limits. However, challenges such as decoherence and time-dependent errors hinder…

Quantum Physics · Physics 2025-02-18 Yulong Dong , Jonathan A. Gross , Murphy Yuezhen Niu

Mobile communication networks were designed to mainly support ubiquitous wireless communications, yet they are also expected to achieve radio sensing capabilities in the near future. However, most prior studies on radio sensing usually rely…

Information Theory · Computer Science 2023-03-13 Huizhi Wang , Zhiqiang Xiao , Yong Zeng

We derive a vector generalization of the curvature-corrected Cram\'er--Rao bound (CRB) in the nonasymptotic regime using a Hilbert space square-root embedding. Building on previous scalar results, we establish a \emph{directional} curvature…

Statistics Theory · Mathematics 2026-03-11 Sunder Ram Krishnan

We derive an algorithm to compute satisfiability bounds for arbitrary {\omega}-regular properties in an Interval-valued Markov Chain (IMC) interpreted in the adversarial sense. IMCs generalize regular Markov Chains by assigning a range of…

Systems and Control · Computer Science 2018-09-18 Maxence Dutreix , Samuel Coogan

Quantum correlations may be measured by means of the distance of the state to the subclass of states $\Omega$ having well defined classical properties. In particular, a geometric measure of asymmetric discord [Dakic et al., Phys. Rev. Lett.…

Quantum Physics · Physics 2012-12-06 Adam Miranowicz , Pawel Horodecki , Ravindra W. Chhajlany , Jan Tuziemski , Jan Sperling

For a pair of incompatible quantum measurements, the total uncertainty can be bounded by a state-independent constant. However, such a bound can be violated if the quantum system is entangled with another quantum system (called memory); the…

Quantum Physics · Physics 2022-03-17 Jin-Long Huang , Wen-Cong Gan , Yunlong Xiao , Fu-Wen Shu , Man-Hong Yung

In quantum computation, amplitude estimation is a fundamental subroutine that is utilized in various quantum algorithms. A general important task of such estimation problems is to characterize the estimation lower bound, which is referred…

Quantum Physics · Physics 2025-07-10 Kohei Oshio , Yohichi Suzuki , Kaito Wada , Keigo Hisanaga , Shumpei Uno , Naoki Yamamoto

Critical quantum metrology exploits the hypersensitivity of quantum systems near phase transitions to achieve enhanced precision in parameter estimation. While single-parameter estimation near critical points is well established, the…

Quantum Physics · Physics 2026-04-08 Luca Previdi , Yilun Xu , Qiongyi He , Matteo G. A. Paris

Autonomous driving and advanced active safety features require accurate high-resolution sensing capabilities. Automotive radars are the key component of the vehicle sensing suit. However, when these radars operate in proximity to flat…

Signal Processing · Electrical Eng. & Systems 2023-05-15 Moshe Levy-Israel , Igal Bilik , Joseph Tabrikian

Quantum bits, or qubits, are the fundamental building blocks of present quantum computers. Hence, it is important to be able to characterize the state of a qubit as accurately as possible. By evaluating the qubit characterization problem…

Quantum Physics · Physics 2024-02-27 Bacui Li , Lorcan O. Conlon , Ping Koy Lam , Syed M. Assad

A fundamental challenge in multiparameter persistent homology is the absence of a complete and discrete invariant. To address this issue, we propose an enhanced framework that realizes a holistic understanding of a fully commutative…

Algebraic Topology · Mathematics 2023-11-14 Yasuaki Hiraoka , Ken Nakashima , Ippei Obayashi , Chenguang Xu

Quantum criticality has been demonstrated as a useful quantum resource for parameter estimation. This includes second-order, topological and localization transitions. In all these works reported so far, gap-to-gapless transition at…

Quantum Physics · Physics 2025-12-29 Sayan Mondal , Ayan Sahoo , Ujjwal Sen , Debraj Rakshit

The Heisenberg uncertainty principle shows that no one can specify the values of the non-commuting canonically conjugated variables simultaneously. However, the uncertainty relation is usually applied to two incompatible measurements. We…

Quantum Physics · Physics 2015-09-22 Jun Zhang , Yang Zhang , Chang-shui Yu

In the context of multiparameter quantum estimation theory, we investigate the construction of linear schemes in order to infer two classical parameters that are encoded in the quadratures of two quantum coherent states. The optimality of…

Quantum Physics · Physics 2019-10-15 M. Arnhem , E. Karpov , N. J. Cerf