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We analyze the information that one can learn about the state of a quantum two-level system, i.e. a qubit, when probed weakly by a nearby detector. In particular, we focus on the case when the qubit Hamiltonian and the qubit's operator…

Quantum Physics · Physics 2009-08-15 S. Ashhab , J. Q. You , Franco Nori

The asymptotic quantum trajectory of weak continuous measurement for the magnetometer is investigated. The magnetometer refers to a setup where the field-to-estimate and the measured moment are orthogonal, and the quantum state is governed…

Quantum Physics · Physics 2023-11-06 Chungwei Lin , Yanting Ma , Dries Sels

We consider simultaneous and continuous measurement of two noncommutative observables of the system whose commutator is not necessarily a $c$-number. We revisit the Arthurs-Kelly model and generalize it to describe the simultaneous…

Quantum Physics · Physics 2021-01-13 Chao Jiang , Gentaro Watanabe

Quantum measurement of a solid-state qubit by a mesoscopic detector is of fundamental interest in quantum physics and an essential issue in quantum computing. In this work, by employing a unified quantum master equation approach constructed…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Xin-Qi Li , Wen-Kai Zhang , Ping Cui , Jiushu Shao , Zhongshui Ma , YiJing Yan

We propose a general theoretical approach to quantum measurements based on the path (histories) summation technique. For a given dynamical variable A, the Schr\"odinger state of a system in a Hilbert space of arbitrary dimensionality is…

Quantum Physics · Physics 2007-05-23 D. Sokolovski , R. Sala Mayato

We consider the problem of continuous quantum measurement of coherent oscillations between two quantum states of an individual two-state system. It is shown that the interplay between the information acquisition and the backaction dephasing…

Mesoscale and Nanoscale Physics · Physics 2009-10-31 A. N. Korotkov , D. V. Averin

The length of time that a quantum system can exist in a superposition state is determined by how strongly it interacts with its environment. This interaction entangles the quantum state with the inherent fluctuations of the environment. If…

Quantum Physics · Physics 2013-10-15 K. W. Murch , S. J. Weber , C. Macklin , I. Siddiqi

Entanglement is a fundamental feature of quantum mechanics and holds great promise for enhancing metrology and communications. Much of the focus of quantum metrology so far has been on generating highly entangled quantum states that offer…

Quantum estimation involving multiple parameters remains an important problem of both theoretical and practical interest. In this work, we study the problem of simultaneous estimation of two parameters that are respectively associate with…

Quantum Physics · Physics 2022-03-25 Yink Loong Len

The present work is motivated by the question as to what aspect of correlation entailed by the two-qubit state serves as the appropriate quantitative resource for steering. To this end, considering Bell-diagonal states, suitable measures of…

Quantum Physics · Physics 2019-05-28 C. Jebarathinam , Aiman Khan , Som Kanjilal , Dipankar Home

Quantum state elimination measurements tell us what states a quantum system does not have. This is different from state discrimination, where one tries to determine what the state of a quantum system is, rather than what it is not. Apart…

Application of the path-integral approach to continuous measurements leads to effective Lagrangians or Hamiltonians in which the effect of the measurement is taken into account through an imaginary term. We apply these considerations to…

Quantum Physics · Physics 2009-10-30 Michael B. Mensky , Roberto Onofrio , Carlo Presilla

Measurement and feedback control are essential features of quantum science, with applications ranging from quantum technology protocols to information-to-work conversion in quantum thermodynamics. Theoretical descriptions of feedback…

This thesis offers novel strategies for the measurement of quantum correlations present in controllable quantum systems, as well as for a full-fledged implementation of the models of light-matter interaction through which these correlations…

Quantum Physics · Physics 2016-11-30 Julen S. Pedernales

Quantum coherence, incompatibility, and quantum correlations are fundamental features of quantum physics. A unified view of those features is crucial for revealing quantitatively their intrinsic connections. We define the relative quantum…

Quantum Physics · Physics 2017-05-30 Ming-Liang Hu , Heng Fan

We show that measurements of finite duration performed on an open two-state system can protect the initial state from a phase-noisy environment, provided the measured observable does not commute with the perturbing interaction. When the…

In this work we analyze a non-commutativity measure of quantum correlations recently proposed by Y. Guo [Sci. Rep. 6, 25241 (2016)]. By recourse to a systematic survey of a two-qubit system, we detected an undesirable behavior of such a…

Quantum Physics · Physics 2017-08-25 A. P. Majtey , D. Bussandri , T. M. Osán , P. W. Lamberti , A. Valdés-Hernández

We demonstrate that the task of determining an unknown quantum state can be accomplished efficiently by making a sequential measurement of two observables $\hat{A}$ and $\hat{B}$, provided that the two observables are chosen in such a way…

Quantum Physics · Physics 2013-10-22 Antonio Di Lorenzo

The possibility of performing simultaneous measurements in quantum mechanics is investigated in the context of the Curie-Weiss model for a projective measurement. Concretely, we consider a spin-$\frac{1}{2}$ system simultaneously…

Quantum Physics · Physics 2017-06-01 Martí Perarnau-Llobet , Theo M. Nieuwenhuizen

We calculate the propagator of a particle caught in a Paul trap and subject to the continuous quantum measurement of its position. The probabilities of the measurement outputs, the possible trajectories of the particle, are also found. This…

Quantum Physics · Physics 2009-10-31 A. Camacho , A. Camacho-Galvan