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A central task in quantum metrology is to exploit quantum correlations to outperform classical sensitivity limits. Metrologically useful entanglement is identified when the quantum Fisher information (QFI) exceeds a separability bound for a…

Quantum Physics · Physics 2025-03-11 Satoya Imai , Augusto Smerzi , Luca Pezzè

We establish a quantum Fisher information (QFI) duality for distributed quantum sensor networks with local phase encoding. For any $N$-qubit probe state, where $N$ denotes the number of sensors, $F_Q(\boldsymbol{w}^\top \boldsymbol{\theta})…

Quantum Physics · Physics 2026-05-21 Farhad Farokhi

Gaussian quantum channels constitute a cornerstone of continuous-variable quantum information science, underpinning a wide array of protocols in quantum optics and quantum metrology. While the action of such channels on arbitrary states is…

Quantum Physics · Physics 2026-02-24 Pritam Chattopadhyay , Saikat Sur , Jonas F. G. Santos

We introduce a new kind of quantum measurement that is defined to be symmetric in the sense of uniform Fisher information across a set of parameters that injectively represent pure quantum states in the neighborhood of a fiducial pure…

Quantum Physics · Physics 2016-05-11 Nan Li , Christopher Ferrie , Jonathan A. Gross , Amir Kalev , Carlton M. Caves

A nonlocal quantum approach is presented to polarimetry, leveraging the phenomenon of entanglement in photon pairs to enhance the precision in sample property determination. By employing two distinct channels, one containing the sample of…

Quantum Physics · Physics 2025-01-30 Ali Pedram , Vira R. Besaga , Frank Setzpfandt , Özgür E. Müstecaplıoğlu

The Fisher information of a quantum observable is shown to be proportional to both (i) the difference of a quantum and a classical variance, thus providing a measure of nonclassicality; and (ii) the rate of entropy increase under Gaussian…

Quantum Physics · Physics 2009-10-31 Michael J. W. Hall

Quantum metrology is a rapidly developing branch of quantum technologies. While various theories have been established on quantum metrology for Markovian processes, i.e., quantum channel estimation, quantum metrology for non-Markovian…

Quantum Physics · Physics 2021-08-04 Anian Altherr , Yuxiang Yang

Continuous quantum metrology holds promise for realizing high-precision sensing by harnessing information progressively carried away by the radiation quanta emitted into the environment. Despite recent progress, a comprehensive…

Quantum Physics · Physics 2026-01-21 Kazuki Yokomizo , Aashish A. Clerk , Yuto Ashida

Quantum criticality, as a fascinating quantum phenomenon, may provide significant advantages for quantum sensing. Here we propose a dynamic framework for quantum sensing with a family of Hamiltonians that undergo quantum phase transitions…

Quantum Physics · Physics 2021-01-20 Yaoming Chu , Shaoliang Zhang , Baiyi Yu , Jianming Cai

Quantum technologies work by utilizing properties inherent in quantum systems such as quantum coherence and quantum entanglement and are expected to be superior to classical counterparts for solving certain problems in science and…

Quantum Physics · Physics 2023-04-10 Yusuke Hama , Hirofumi Nishi

We demonstrate that multipartite entanglement, witnessed by the quantum Fisher information (QFI), can characterize topological quantum phase transitions in the spin-$\frac{1}{2}$ toric code model on a square lattice with external fields. We…

Quantum Physics · Physics 2022-06-14 Yu-Ran Zhang , Yu Zeng , Tao Liu , Heng Fan , J. Q. You , Franco Nori

The subjects of the paper are the likelihood method (LM) and the expected Fisher information (FI) considered from the point od view of the construction of the physical models which originate in the statistical description of phenomena. The…

Data Analysis, Statistics and Probability · Physics 2013-10-08 E. W. Piotrowski , J. Sladkowski , J. Syska , S. Zajac

Critical properties of a quantum system are recognized as valuable resources for quantum metrology. In this work, we investigate the criticality-enhanced sensing in a quantum Rabi triangle system, which exhibits multiple phases. Around the…

Quantum Physics · Physics 2025-11-04 Yuyang Tang , Yu Yang , Min An , Fuli Li

Fragile quantum features such as entanglement are employed to improve the precision of parameter estimation and as a consequence the quantum gain becomes vulnerable to noise. As an established tool to subdue noise, quantum error correction…

Quantum Physics · Physics 2015-06-09 Xiao-Ming Lu , Sixia Yu , C. H. Oh

Precision measurements with quantum systems rely on our ability to trace the differences between experimental signals to variations in unknown physical parameters. In this Letter we derive the Fisher information and the ensuing Cramer-Rao…

Quantum Physics · Physics 2015-06-17 Søren Gammelmark , Klaus Mølmer

Using inelastic X-ray scattering (IXS), we experimentally investigate the quantum geometry and quantum information in the large-gap insulator, LiF. Using sum rules for the density-density response function measured in IXS, we compute the…

Mesoscale and Nanoscale Physics · Physics 2025-05-16 David Bałut , Barry Bradlyn , Peter Abbamonte

In this work, we study the quantum Fisher information (QFI) per particle of an open (particles can enter and leave the system) and dissipative (far from thermodynamical equilibrium) steady state system of two qubits in noisy channels. We…

Quantum Physics · Physics 2016-10-07 Azmi Ali Altintas

The quantum Fisher information is of considerable interest not only for quantum metrology but also because it is a useful entanglement measure for finite temperature mixed states. In particular, it estimates the degree to which multipartite…

Strongly Correlated Electrons · Physics 2019-02-15 James Lambert , Erik Sorensen

In this paper we reconsider the single parameter quantum Fisher information (QFI) and compare it with the two-parameter one. We find simple relations connecting the single parameter QFI (both in the asymmetric and symmetric phase shift…

Quantum Physics · Physics 2020-07-08 Stefan Ataman

We use the quantum Fisher information (QFI) to diagnose a dynamical phase transition (DPT) in a closed quantum system, which is usually defined in terms of non-analytic behaviour of a time-averaged order parameter. Employing the…

Quantum Physics · Physics 2021-09-08 Qingze Guan , Robert J. Lewis-Swan