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Bayesian inference is a widely used technique for real-time characterization of quantum systems. It excels in experimental characterization in the low data regime, and when the measurements have degrees of freedom. A decisive factor for its…

Quantum Physics · Physics 2025-07-10 Alexandra Ramôa , Raffaele Santagati , Nathan Wiebe

We address the characterization of two-qubit gates, focusing on bounds to precision in the joint estimation of the three parameters that define their Cartan decomposition. We derive the optimal probe states that jointly maximize precision,…

Quantum Physics · Physics 2025-02-13 Gabriele Fazio , Jiayu He , Matteo G. A. Paris

Bayesian error analysis paves the way to the construction of credible and plausible error regions for a point estimator obtained from a given dataset. We introduce the concept of region accuracy for error regions (a generalization of the…

Quantum Physics · Physics 2019-07-15 Changhun Oh , Yong Siah Teo , Hyunseok Jeong

For the efficient implementation of quantum algorithms, practical ways to generate many-body entanglement are a basic requirement. Specifically, coupling multiple qubit pairs at once can be advantageous and can lead to multi-qubit…

Quantum Physics · Physics 2022-09-30 Maximilian Nägele , Christian Schweizer , Federico Roy , Stefan Filipp

The Bayesian Cram\'er-Rao bound (CRB) provides a lower bound on the mean square error of any Bayesian estimator under mild regularity conditions. It can be used to benchmark the performance of statistical estimators, and provides a…

Machine Learning · Statistics 2024-09-09 Evan Scope Crafts , Xianyang Zhang , Bo Zhao

The accurate and reliable description of measurement devices is a central problem in both observing uniquely non-classical behaviors and realizing quantum technologies from powerful computing to precision metrology. To date quantum…

Quantum Physics · Physics 2020-01-30 Aonan Zhang , Jie Xie , Huichao Xu , Kaimin Zheng , Han Zhang , Yiu-Tung Poon , Vlatko Vedral , Lijian Zhang

We derive a family of optimal protocols, in the sense of saturating the quantum Cram\'{e}r-Rao bound, for measuring a linear combination of $d$ field amplitudes with quantum sensor networks, a key subprotocol of general quantum sensor…

Quantum Physics · Physics 2023-10-03 Adam Ehrenberg , Jacob Bringewatt , Alexey V. Gorshkov

The Cram\'er-Rao bound serves as a crucial lower limit for the mean squared error of an estimator in frequentist parameter estimation. Paradoxically, it requires highly accurate prior knowledge of the estimated parameter for constructing…

Quantum Physics · Physics 2025-04-21 Javier Navarro , Ricard Ravell Rodríguez , Mikel Sanz

This paper derives a general expression for the Cram\'er-Rao bound (CRB) of wireless localization algorithms using range measurements subject to bias corruption. Specifically, the a priori knowledge about which range measurements are…

Information Theory · Computer Science 2011-11-10 Tao Wang

We present an inference method utilizing artificial neural networks for parameter estimation of a quantum probe monitored through a single continuous measurement. Unlike existing approaches focusing on the diffusive signals generated by…

We present filtering equations for single shot parameter estimation using continuous quantum measurement. By embedding parameter estimation in the standard quantum filtering formalism, we derive the optimal Bayesian filter for cases when…

Quantum Physics · Physics 2009-02-13 Bradley A. Chase , J. M. Geremia

In a unified viewpoint in quantum channel estimation, we compare the Cramer-Rao and the mini-max approaches, which gives the Bayesian bound in the group covariant model. For this purpose, we introduce the local asymptotic mini-max bound,…

Quantum Physics · Physics 2011-06-24 Masahito Hayashi

We analyse the precision limits for simultaneous estimation of a pair of conjugate parameters in a displacement channel using Gaussian probes. Having a set of squeezed states as an initial resource, we compute the Holevo Cram\'er-Rao bound…

Quantum Physics · Physics 2020-05-27 Syed M. Assad , Jiamin Li , Yuhong Liu , Ningbo Zhao , Wen Zhao , Ping Koy Lam , Z. Y. Ou , Xiaoying Li

We present optimal measuring strategies for the estimation of the entanglement of unknown two-qubit pure states and of the degree of mixing of unknown single-qubit mixed states, of which N identical copies are available. The most general…

Quantum Physics · Physics 2009-10-31 A. Acin , R. Tarrach , G. Vidal

A recently proposed phase-estimation protocol that is based on measuring the parity of a two-mode squeezed-vacuum state at the output of a Mach-Zehnder interferometer shows that Cram\'{e}r-Rao bound sensitivity can be obtained [P.\ M.\…

Quantum Physics · Physics 2013-09-10 Keith R. Motes , Petr M. Anisimov , Jonathan P. Dowling

We carefully examine critical metrology and present an improved critical quantum metrology protocol which relies on quenching a system exhibiting a superradiant quantum phase transition beyond its critical point. We show that this approach…

Quantum Physics · Physics 2022-05-04 Karol Gietka , Lewis Ruks , Thomas Busch

Phase diagrams chart material properties with respect to one or more external or internal parameters such as pressure or magnetisation; as such, they play a fundamental role in many theoretical and applied fields of science. In this work,…

Quantum Physics · Physics 2021-05-28 James D. Watson , Johannes Bausch

Quantum parameter estimation holds the promise of quantum technologies, in which physical parameters can be measured with much greater precision than what is achieved with classical technologies. However, how to obtain a best precision when…

Quantum Physics · Physics 2024-03-05 Jianning Li , Dianzhen Cui , X. X. Yi

Using quantum systems as sensors or probes has been shown to greatly improve the precision of parameter estimation by exploiting unique quantum features such as entanglement. A major task in quantum sensing is to design the optimal…

Quantum Physics · Physics 2024-06-24 Jessica Bavaresco , Patryk Lipka-Bartosik , Pavel Sekatski , Mohammad Mehboudi

A pivotal task in quantum metrology, and quantum parameter estimation in general, is to de- sign schemes that achieve the highest precision with given resources. Standard models of quantum metrology usually assume the dynamics is fixed, the…

Quantum Physics · Physics 2017-07-18 Jing Liu , Haidong Yuan
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