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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 present the time dynamics of twisted quantum states. We find an explicit connection between the well-known stationary Landau state and an evolving twisted state, even when the Hamiltonian accounts for linear energy dissipation. Utilizing…

Quantum Physics · Physics 2023-09-06 N. V. Filina , S. S. Baturin

We characterize the long-time projective behavior of the stochastic master equation describing a continuous, collective spin measurement of an atomic ensemble both analytically and numerically. By adding state based feedback, we show that…

Quantum Physics · Physics 2007-05-23 John K. Stockton , Ramon van Handel , Hideo Mabuchi

We consider 1-qubit mixed quantum state estimation by adaptively updating measurements according to previously obtained outcomes and measurement settings. Updates are determined by the average-variance-optimality (A-optimality) criterion,…

Quantum Physics · Physics 2012-05-21 Takanori Sugiyama , Peter S. Turner , Mio Murao

We propose a new approach to study the evolution of a quantum state that is encoded in a system which is continuously subject to the operations required to implement a quantum error correcting code. In the limit of continuous error…

Quantum Physics · Physics 2007-05-23 Juan Pablo Paz , Wojciech Hubert Zurek

We present a general formalism based on the variational principle for finding the time-optimal quantum evolution of mixed states governed by a master equation, when the Hamiltonian and the Lindblad operators are subject to certain…

Quantum Physics · Physics 2014-12-01 A. Carlini , A. Hosoya , T. Koike , Y. Okudaira

Quantum measurements are crucial to observe the properties of a quantum system, which however unavoidably perturb its state and dynamics in an irreversible way. Here we study the dynamics of a quantum system while being subject to a…

We study quantum tomography based on a stochastic continuous-time measurement record obtained from a probe field collectively interacting with an ensemble of identically prepared systems. In comparison to previous studies, we consider here…

Quantum Physics · Physics 2014-10-01 Robert L. Cook , Carlos A. Riofrío , Ivan H. Deutsch

We consider the problem of determining the state of a quantum system given one or more readings of the expectation value of an observable. The system is assumed to be a finite dimensional quantum control system for which we can influence…

Quantum Physics · Physics 2009-11-10 Domenico D'Alessandro

The standard approach to quantum measurements is to assume that they lead to effectively instantaneous collapse of the quantum state. However, if we assume that we are unable to enforce at what exact moment of time the measurement occurs…

Quantum Physics · Physics 2026-03-20 Igor Prlina , Milutin Živković

We propose replacing the instantaneous state reduction in von Neumann selective measurement with continuous nonlinear evolution. Despite its nonlinearity, this evolution preserves the equivalence of quantum ensembles and hence obeys the…

Quantum Physics · Physics 2026-05-19 Jakub Rembieliński , Karol Ławniczak

The possibility of determining the state of a quantum system after a continuous measurement of position is discussed in the framework of quantum trajectory theory. Initial lack of knowledge of the system and external noises are accounted…

Quantum Physics · Physics 2009-10-31 A. C. Doherty , S. M. Tan , A. S. Parkins , D. F. Walls

We derive the master equation that governs the evolution of the measured state backwards in time in an open system. This allows us to determine probabilities for a given set of preparation events from the results of subsequent measurements,…

Quantum Physics · Physics 2016-09-08 Stephen M. Barnett , David T. Pegg , John Jeffers , Ottavia Jedrkiewicz

We address the statistics of a simultaneous CWLM of two non-commuting variables on a few-state quantum system subject to a conditioned evolution. Both conditioned quantum measurement and that of two non-commuting variables differ…

Quantum Physics · Physics 2019-12-11 A. Franquet , Yuli V. Nazarov

We address the issue of coupling variables which are essentially classical to variables that are quantum. Two approaches are discussed. In the first (based on collaborative work with L.Di\'osi), continuous quantum measurement theory is used…

General Relativity and Quantum Cosmology · Physics 2009-10-31 J. J. Halliwell

In this work we study the unitary time-evolutions of quantum systems defined on infinite-dimensional separable time-dependent Hilbert spaces. Two possible cases are considered: a quantum system defined on a stochastic interval and another…

Quantum Physics · Physics 2019-05-22 Luca Curcuraci , Stefano Bacchi , Angelo Bassi

We propose to experimentally test non-deterministic time evolution in quantum mechanics by consecutive measurements of non-commuting observables on the same prepared state. While in the standard theory the measurement outcomes are…

Quantum Physics · Physics 2011-08-02 Sabine Hossenfelder

The exact statistics of an arbitrary quantum observable is analytically obtained. Due to the probabilistic nature of a sequence of intermediate measurements and stochastic fluctuations induced by the interaction with the environment, the…

Statistical Mechanics · Physics 2019-06-19 Stefano Gherardini

The Gaussian state description of continuous variables is adapted to describe the quantum interaction between macroscopic atomic samples and continuous-wave light beams. The formalism is very efficient: a non-linear differential equation…

Quantum Physics · Physics 2007-05-23 L. B. Madsen , K. Mølmer

We address the statistics of continuous weak linear measurement on a few-state quantum system that is subject to a conditioned quantum evolution. For a conditioned evolution, both the initial and final states of the system are fixed: the…

Quantum Physics · Physics 2017-02-23 A. Franquet , Yuli V. Nazarov