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Quantum-enhanced interferometry is often discussed in terms of ideal resources and asymptotic scalings, whereas in practice its performance is set by a delicate interplay between losses, state imbalance, and photon number. We address this…

Squeezed-state interferometry plays an important role in quantum-enhanced optical phase estimation, as it allows the estimation precision to be improved up to the Heisenberg limit by using ideal photon-number-resolving detectors at the…

Quantum Physics · Physics 2017-02-22 P. Liu , P. Wang , W. Yang , G. R. Jin , C. P. Sun

We present a method to estimate the quantum Fisher information (QFI) of many-body quantum states in the presence of decoherence, where its direct evaluation requires the full spectral resolution of the density matrix. We show that, for…

Quantum Physics · Physics 2026-05-25 Francesco Musso , Vittorio Vitale , Sara Murciano

Quantum Fisher information (QFI) plays a vital role in quantum precision measurement, quantum information, many-body physics, and other domains. Obtaining the QFI from experiment for a quantum state reveals insights such as the limits of…

Quantum Physics · Physics 2024-08-26 Qi Liu

We study the quantum Fisher information (QFI) per particle of an open (parti- cles can enter and leave the system) and dissipative (far from thermodynamical equilibrium) steady state system of two qubits in a noise which is decoherence. We…

Quantum Physics · Physics 2016-02-23 Azmi Ali Altintas

Quantum sensors driven into the quantum chaotic regime can have dramatically enhanced sensitivity, which, however, depends intricately on the details of the underlying classical phase space. Here, we develop an accurate semiclassical…

Quantum Physics · Physics 2026-01-26 Mahdi RouhbakhshNabati , Daniel Braun , Henning Schomerus

We theoretically derive the lower and upper bounds of quantum Fisher information (QFI) of an SU(1,1) interferometer whatever the input state chosen. According to the QFI, the crucial resource for quantum enhancement is shown to be large…

Quantum Physics · Physics 2017-09-13 Qian-Kun Gong , Dong Li , Chun-Hua Yuan , Z. Y. Ou , Weiping Zhang

Quantum metrology has an important role in the fields of quantum optics and quantum information processing. Here we introduce a kind of non-Gaussian state, Laguerre excitation squeezed state as input of traditional Mach-Zehnder…

Quantum Physics · Physics 2023-05-24 Zekun Zhao , Huan Zhang , Yibing Huang , Liyun Hu

We investigate an optimal distance of two components in an entangled coherent state for quantum phase estimation in lossy interferometry. The optimal distance is obtained by an economical point, representing the quantum Fisher information…

Quantum Physics · Physics 2020-01-28 Su-Yong Lee , Yong Sup Ihn , Zaeill Kim

The Quantum Fisher information (QFI) quantifies the ultimate precision of estimating a parameter from a quantum state, and can be regarded as a reliability measure of a quantum system as a quantum sensor. However, estimation of the QFI for…

Quantum Physics · Physics 2022-02-03 Jacob L. Beckey , M. Cerezo , Akira Sone , Patrick J. Coles

Given a quantum state with an unknown parameter, the Quantum Fisher Information (QFI) is a measure of the amount of information that an observable can extract about the parameter. QFI also quantifies the maximum achievable precision in…

Quantum Physics · Physics 2019-08-19 C. S. Sudheer Kumar , T. S. Mahesh

Quantum Fisher Information (QFI) is a measure quantifying the sensitivity of a quantum state with respect to changes in tuning parameters in quantum metrology, and defining quantum speed limits. We show that even if the quantum state is…

Quantum Physics · Physics 2025-07-23 Alexander Kruchkov

We deal with the maximization of classical Fisher information in a quantum system depending on an unknown parameter. This problem has been raised by physicists, who defined [Helstrom (1967) Phys. Lett. A 25 101-102] a quantum counterpart of…

Statistics Theory · Mathematics 2007-06-13 Alessandra Luati

We study the phase super-sensitivity of a Mach-Zehnder interferometer (MZI) with the squeezed Kerr and coherent states as the inputs. We discuss the lower bound in phase sensitivity by considering the quantum Fisher information (QFI) and…

Quantum Physics · Physics 2024-04-04 Dhiraj Yadav , Gaurav Shukla , Priyanka Sharma , Devendra Kumar Mishra

Quantum Fisher information matrix (QFIM) is a core concept in theoretical quantum metrology due to the significant importance of quantum Cram\'{e}r-Rao bound in quantum parameter estimation. However, studies in recent years have revealed…

Quantum Physics · Physics 2020-03-27 Jing Liu , Haidong Yuan , Xiao-Ming Lu , Xiaoguang Wang

In this paper, we study the ground state Quantum Fisher Information (QFI) in one-dimensional spin-1 models, as witness to Multipartite Entanglement. The models addressed are the Bilinear-Biquadratic model, the most general isotropic…

The quantum Fisher information (QFI) of certain multipartite entangled quantum states is larger than what is reachable by separable states, providing a metrological advantage. Are these nonclassical correlations strong enough to potentially…

Quantum Physics · Physics 2019-05-03 Florian Fröwis , Matteo Fadel , Philipp Treutlein , Nicolas Gisin , Nicolas Brunner

Quantum Fisher information (QFI) is an important feature for the precision of quantum parameter estimation based on the quantum Cram\'er-Rao inequality. When the quantum state satisfies the von Neumann-Landau equation, the local quantum…

Quantum Physics · Physics 2018-02-27 Shao-xiong Wu , Yang Zhang , Chang-shui Yu

Quantum-enhanced sensing is commonly benchmarked using the quantum Fisher information (QFI), often interpreted as a direct indicator of achievable precision. However, this quantity acquires operational meaning only within a fully specified…

Quantum Physics · Physics 2026-03-10 Zdeněk Hradil , Jaroslav Řeháček

We present the experimental measurement, on a quantum processor, of a series of polynomial lower bounds that converge to the quantum Fisher information (QFI), a fundamental quantity for certifying multipartite entanglement that is useful…