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Achieving ultimate bounds in estimation processes is the main objective of quantum metrology. In this context, several problems require measurement of multiple parameters by employing only a limited amount of resources. To this end,…

We investigate quantum sensing for spectroscopy in a system consisting of a two-level atom coupled to a continuum of modes. We focus on optimizing the pulse shape of a coherent state to maximize the quantum Fisher information (QFI) of the…

Quantum Physics · Physics 2025-09-15 Karthik Chinni , Nicolás Quesada

Quantum interferometry methods exploit quantum resources, such as photonic entanglement, to enhance phase estimation beyond classical limits. Nonlinear optics has served as a workhorse for the generation of entangled photon pairs, ensuring…

Quantum Physics · Physics 2025-08-04 Romain Dalidet , Anthony Martin , Grégory Sauder , Laurent Labonté , Sébastien Tanzilli

We propose a method for optical interferometry in telescope arrays assisted by quantum networks. In our approach, the quantum state of incoming photons along with an arrival time index is stored in a binary qubit code at each receiver.…

The aim of this thesis is to develop a theoretical framework to study parameter estimation of quantum channels. We study the task of estimating unknown parameters encoded in a channel in the sequential setting. A sequential strategy is the…

Quantum Physics · Physics 2022-01-06 Vishal Katariya

We show that localisation microscopy of multiple weak, incoherent point sources with possibly different intensities in one spatial dimension is equivalent to estimating the amplitudes of a classical mixture of coherent states of a simple…

Quantum Physics · Physics 2020-02-17 Evangelia Bisketzi , Dominic Branford , Animesh Datta

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

We identify precision limits for the simultaneous estimation of multiple parameters in multimode interferometers. Quantum strategies to enhance the multiparameter sensitivity are based on entanglement among particles, modes or combining…

Quantum Physics · Physics 2018-10-01 Manuel Gessner , Luca Pezzè , Augusto Smerzi

We present the quantum theory of the measurement of bosonic particles by multipixel detectors. For the sake of clarity, we specialize on beams of photons. We study the measurement of different spatial beam characteristics, as position and…

Quantum Physics · Physics 2016-09-13 Vanessa Chille , Nicolas Treps , Claude Fabre , Gerd Leuchs , Christoph Marquardt , Andrea Aiello

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

Optically localizing a single quasi-monochromatic source to sub-diffractive precisions entails, in the photon-counting limit, a minimum photon cost that scales as the squared ratio of the width, $w$, of the optical system's point-spread…

Quantum Physics · Physics 2020-10-07 Sudhakar Prasad

Quantum estimation of parameters defining open-system dynamics may be enhanced by using ancillas that are entangled with the probe but are not submitted to the dynamics. Here we consider the important problem of estimation of transmission…

Quantum Physics · Physics 2024-03-04 Jiaxuan Wang , Ruynet. L. de Matos Filho , Girish S. Agarwal , Luiz Davidovich

The estimation of multiple parameters is a ubiquitous requirement in many quantum metrology applications. However, achieving the ultimate precision limit, i.e. the quantum Cram\'er-Rao bound, becomes challenging in these scenarios compared…

Quantum Physics · Physics 2024-11-25 Ben Wang , Kaimin Zheng , Qian Xie , Aonan Zhang , Liang Xu , Lijian Zhang

Quantum metrology derives its capabilities from the careful employ of quantum resources for carrying out measurements. This advantage, however, relies on refined data postprocessing, assessed based on the variance of the estimated…

Extracting information from weak optical signals is a critical challenge across a broad range of technologies. Conventional imaging techniques, constrained to integrating over detected signals and classical post-processing, are limited in…

Quantum Physics · Physics 2025-12-18 Aleksandr Mokeev , Babak Saif , Mikhail D. Lukin , Johannes Borregaard

High-precision sensors that exploit uniquely quantum phenomena have been shown to surpass the standard quantum limit of measurement precision. However, in the general scenario where multiple parameters are simultaneously encoded in a…

Quantum Physics · Physics 2025-10-20 Berihu Teklu , Victor Montenegro

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

Quantum Channel Discrimination (QCD) presents a fundamental task in quantum information theory, with critical applications in quantum reading, illumination, data-readout and more. The extension to multiple quantum channel discrimination has…

Quantum Physics · Physics 2021-05-12 Cillian Harney , Leonardo Banchi , Stefano Pirandola

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 entanglement and squeezing have significantly improved phase estimation and imaging in interferometric settings beyond the classical limits. However, for a wide class of non-interferometric phase imaging/retrieval methods vastly…