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We address the problem of continuous-variable quantum phase estimation in the presence of linear disturbance at the Hamiltonian level, by means of Gaussian probe states. In particular we discuss both unitary and random disturbance, by…

Quantum Physics · Physics 2015-01-26 Douglas Delgado de Souza , Marco G. Genoni , M. S. Kim

How precisely can we estimate cosmological parameters by performing a quantum measurement on a cosmological quantum state? In quantum estimation theory the variance of an unbiased parameter estimator is bounded from below by the inverse of…

General Relativity and Quantum Cosmology · Physics 2017-10-17 Marcello Rotondo , Yasusada Nambu

We establish the necessary and sufficient conditions for unbiased estimation in multi-parameter estimation tasks. More specifically, we first consider quantum state estimation, where multiple parameters are encoded in a quantum state, and…

Quantum Physics · Physics 2026-03-03 Hyukgun Kwon , Kento Tsubouchi , Chia-Tung Chu , Liang Jiang

Unlike well-established parameter estimation, function estimation faces conceptual and mathematical difficulties despite its enormous potential utility. We establish the fundamental error bounds on function estimation in quantum metrology…

Quantum Physics · Physics 2020-01-29 Naoto Kura , Masahito Ueda

In this paper we explore the possibility of performing Heisenberg limited quantum metrology of a phase, without any prior, by employing only maximally entangled states. Starting from the estimator introduced by Higgins et al. in New J.…

Quantum Physics · Physics 2020-10-27 Federico Belliardo , Vittorio Giovannetti

In this study the determinant of the average quadratic error matrix is used as the measure of state estimation efficiency. This quantity is easily computable in some cases, so it gives us a reasonable tool to find optimal measurement setup…

Quantum Physics · Physics 2012-01-10 Denes Petz , Laszlo Ruppert

We present efficient circuits that can be used for the phase space tomography of quantum states. The circuits evaluate individual values or selected averages of the Wigner, Kirkwood and Husimi distributions. These quantum gate arrays can be…

Quantum Physics · Physics 2009-11-10 Juan Pablo Paz , Augusto J. Roncaglia , Marcos Saraceno

In the present study, time evolution of quantum Cramer-Rao bound of entangled N00N state, as phase sensitivity, is determined by the aid of quantum estimation theory in the presence decoherence channels. Also, the dynamic quantum process as…

Quantum Physics · Physics 2015-06-23 Farzam Nosraty

The calibration of high-quality two-qubit entangling gates is an essential component in engineering large-scale, fault-tolerant quantum computers. However, many standard calibration techniques are based on randomized circuits that are only…

Quantum systems allow one to sense physical parameters beyond the reach of classical statistics---with resolutions greater than $1/N$, where $N$ is the number of constituent particles independently probing a parameter. In the canonical…

We present a family of easily computable upper bounds for the Holevo quantity of ensemble of quantum states depending on a reference state as a free parameter. These upper bounds are obtained by combining probabilistic and metric…

Quantum Physics · Physics 2019-10-18 M. E. Shirokov

Information metrics give lower bounds for the estimation of parameters. The Cencov-Morozova-Petz Theorem classifies the monotone quantum Fisher metrics. The optimum bound for the quantum estimation problem is offered by the metric which is…

Quantum Physics · Physics 2012-10-09 Demetris P. K. Ghikas , Fotios Oikonomou

Careful tailoring the quantum state of probes offers the capability of investigating matter at unprecedented precisions. Rarely, however, the interaction with the sample is fully encompassed by a single parameter, and the information…

Evaluating the amount of information obtained from non-orthogonal quantum states is an important topic in the field of quantum information. The commonly used evaluation method is Holevo bound, which only provides a loose upper bound for…

Quantum Physics · Physics 2021-09-27 Wei Li , Shengmei Zhao

We analyze quantum state estimation for finite samples based on symmetry information. The used measurement concept compares an unknown qubit to a reference state. We describe explicitly an adaptive strategy, that enhances the estimation…

Quantum Physics · Physics 2009-11-13 Christof J. Happ , Matthias Freyberger

We study the Hilbert-Schmidt measure on the manifold of mixed Gaussian states in multi mode continuous variable quantum systems. An analytical expression for the Hilbert-Schmidt volume element is derived. Its corresponding probability…

Quantum Physics · Physics 2015-03-10 Valentin Link , Walter T. Strunz

We consider the problem of determining the mixed quantum state of a large but finite number of identically prepared quantum systems from data obtained in a sequence of ideal (von Neumann) measurements, each performed on an individual copy…

Quantum Physics · Physics 2009-11-10 Franz Embacher , Heide Narnhofer

Quantum phase estimation is an important component in diverse quantum algorithms. However, it suffers from spectral leakage, when the reciprocal of the record length is not an integer multiple of the unknown phase, which incurs an accuracy…

Quantum Physics · Physics 2022-05-17 Yifeng Xiong , Soon Xin Ng , Gui-Lu Long , Lajos Hanzo

The aim of the channel estimation is to estimate the parameters encoded in a quantum channel. For this aim, it is allowed to choose the input state as well as the measurement to get the outcome. Various precision bounds are known for the…

Quantum Physics · Physics 2024-11-21 Masahito Hayashi , Yingkai Ouyang

We study the connection between exceptional points (EPs) and optimal parameter estimation, in a simple system consisting of two counter-propagating traveling wave modes in a microring resonator. The unknown parameter to be estimated is the…

Quantum Physics · Physics 2025-11-18 Robert L. Cook , Liwen Ko , K. Birgitta Whaley
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