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We investigate the quantum estimation on the Hubble parameter of an expanding de Sitter space by quantum metrological techniques. By exploring the dynamics of a freely falling Unruh-DeWitt detector, which interacts with a scalar field…

High Energy Physics - Theory · Physics 2018-09-12 Xiaoyang Huang , Jun Feng , Yao-Zhong Zhang , Heng Fan

We examine metrological scenarios where the parameter of interest is encoded onto a quantum state through the action of a noisy quantum gate and investigate the ultimate bound to precision by analyzing the behaviour of the Quantum Fisher…

Quantum Physics · Physics 2025-02-18 Giovanni Ragazzi , Simone Cavazzoni , Paolo Bordone , Matteo G. A. Paris

We study, in the framework of open quantum systems, the time evolution of a circularly accelerated two-level atom coupled in the multipolar scheme to a bath of fluctuating vacuum electromagnetic fields. We find that both the spontaneous…

General Relativity and Quantum Cosmology · Physics 2014-07-01 Yao Jin , Jiawei Hu , Hongwei Yu

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

We upper- and lower-bound the optimal precision with which one can estimate an unknown Hamiltonian parameter via measurements of Gibbs thermal states with a known temperature. The bounds depend on the uncertainty in the Hamiltonian term…

Quantum Fisher Information (QFI) is a fundamental quantity in quantum parameter estimation theory, characterizing the ultimate precision bound of parameter estimation. In this work, we investigate QFI for quantum states in non-Hermitian…

Quantum Physics · Physics 2025-05-27 L. H. Wei , H. J. Xing , L. B. Fu , H. D. Liu

We investigate the ultimate quantum limit of resolving the temperatures of two thermal sources affected by the diffraction. More quantum Fisher information can be obtained with the priori information than that without the priori…

Quantum Physics · Physics 2022-11-16 Dong Xie , Chunling Xu , An Min Wang

The quantum Cram\'er-Rao bound sets a fundamental limit on the accuracy of unbiased parameter estimation in quantum systems, relating the uncertainty in determining a parameter to the inverse of the quantum Fisher information. We…

We tackle the issue of estimating dynamical parameters in quantum electrodynamics. We numerically compute the quantum Fisher information matrix (QFIM) of physical parameters in electron-muon and Compton scattering at tree level. In…

Quantum Physics · Physics 2025-09-08 Preslav Asenov , WenHan Zhang , Alessio Serafini

We introduce Quantum Functional Information (QFI), a new metric to quantify the rarity and utility of quantum states and circuits. Unlike standard measures such as fidelity or entropy, QFI captures the balance between functionality and…

Quantum Physics · Physics 2025-09-16 Rodrigo Pasti , Jonas Krause

Optimal control theory is an effective tool to improve parameter estimation of quantum systems. Different methods can be employed for the design of the control protocol. They can be based either on Quantum Fischer Information (QFI)…

Quantum Physics · Physics 2023-06-21 Quentin Ansel , Etienne Dionis , Dominique Sugny

Multipartite entanglement, such as witnessed through the quantum Fisher information (QFI), is a crucial resource for quantum technologies, but its experimental certification is highly challenging. Here, we propose an experimentally friendly…

Quantum Physics · Physics 2021-09-01 Ricardo Costa de Almeida , Philipp Hauke

Quantum speed limits are rigorous estimates on how fast a state of a quantum system can depart from the initial state in the course of quantum evolution. Most known quantum speed limits, including the celebrated Mandelstam-Tamm and…

Quantum Physics · Physics 2021-06-02 Nikolai Il`in , Oleg Lychkovskiy

In the context of quantum speed limits, it has been shown that the minimum time required to cause a desired state conversion via the open quantum dynamics can be estimated using the entropy production. However, the established entropy-based…

Quantum Physics · Physics 2024-10-16 Kotaro Sekiguchi , Satoshi Nakajima , Ken Funo , Hiroyasu Tajima

We investigate the parameter estimation problem in a two-qubit system, in which each qubit is independently interacting with its Markovian environment. We study in detail the sensitivity of the estimation on the decoherence rate $\gamma$…

Quantum Physics · Physics 2014-01-14 Zheng Qiang , Yao Yao , Yong Li

We propose an experimentally accessible scheme to determine lower bounds on the quantum Fisher information (QFI), which ascertains multipartite entanglement or usefulness for quantum metrology. The scheme is based on comparing the…

Quantum Physics · Physics 2016-03-14 Florian Fröwis , Pavel Sekatski , Wolfgang Dür

The mean field approximation is used to investigate the general features of the dynamics of a two-level atom in a ferromagnetic lattice close to the Curie temperature. Various analytical and numerical results are obtained. We first…

Quantum Physics · Physics 2023-07-07 Yamen Hamdouni

We propose a scheme to enhance the range and precision of ultralow temperature measurements by employing a probe qubit coupled to a chain of ancilla qubits. Specifically, we analyze a qubit chain governed by Heisenberg $XX$ and…

Quantum Physics · Physics 2025-02-19 Asghar Ullah , Vipul Upadhyay , Özgür E. Müstecaplıoğlu

The characterization of entanglement is a central problem for the study of quantum many-body dynamics. Here, we propose the quantum Fisher information as a useful tool for the study of multipartite-entanglement dynamics in many-body…

Statistical Mechanics · Physics 2019-02-27 Karol Gietka , Jan Chwedeńczuk , Tomasz Wasak , Francesco Piazza

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
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