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We present a novel approach, based entirely on the gravitational potential, for studying the evolution of non-linear cosmological matter perturbations. Starting from the perturbed Einstein equations, we integrate out the non-relativistic…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 Ram Brustein , Antonio Riotto

We report an alternative scheme for implementing generalized quantum measurements that does not require the usage of auxiliary system. Our method utilizes solely: (a) classical randomness and post-processing, (b) projective measurements on…

Quantum Physics · Physics 2019-08-30 Michał Oszmaniec , Filip B. Maciejewski , Zbigniew Puchała

A one-dimensional quantum oscillator is monitored by taking repeated position measurements. As a first con- tribution, it is shown that, under a quantum nondemolition measurement scheme applied to a system initially at the ground state, (i)…

Quantum Physics · Physics 2015-11-13 Vincenzo Matta , Vincenzo Pierro

We study quantum measurement with preselection and postselection, and derive the precise expressions of the measurement results without any restriction on the coupling strength between the system and the measuring device. For a qubit…

Quantum Physics · Physics 2011-11-18 Xuanmin Zhu , Yuxiang Zhang , Shengshi Pang , Chang Qiao , Quanhui Liu , Shengjun Wu

The measurement problem is to explain why a system which is in a linear combination of states appears, upon measurement, to be in just one of those states. The solution given here is to first show that if one assumes linear, unitary, no…

Quantum Physics · Physics 2013-04-30 Casey Blood

The fact that not all quantum observables are jointly measurable is one of the major differences between quantum and classical theory. In the former, non-commuting observables can only be simultaneously measured with limited precision. We…

Quantum Physics · Physics 2016-10-17 Gilles Pütz , Tomer Barnea , Nicolas Gisin , Anthony Martin

A discussion is given of the quantisation of a physical system with finite degrees of freedom subject to a Hamiltonian constraint by treating time as a constrained classical variable interacting with an unconstrained quantum state. This…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Charles Wang

The measurement of a spin-$\half$ is modeled by coupling it to an apparatus, that consists of an Ising magnetic dot coupled to a phonon bath. Features of quantum measurements are derived from the dynamical solution of the measurement,…

Quantum Physics · Physics 2017-08-23 Armen E. Allahverdyan , Roger Balian , Theo M. Nieuwenhuizen

In textbooks, ideal quantum measurements are described in terms of the tested system only by the collapse postulate and Born's rule. This level of description offers a rather flexible position for the interpretation of quantum mechanics.…

Quantum Physics · Physics 2017-09-28 Theo M. Nieuwenhuizen , Marti Perarnau-Llobet , Roger Balian

The purpose of this paper is to study the problem of generalizing the Belavkin-Kalman filter to the case where the classical measurement signal is replaced by a fully quantum non-commutative output signal. We formulate a least mean squares…

Mathematical Physics · Physics 2015-06-23 Nina H. Amini , Zibo Miao , Yu Pan , Matthew R. James , Hideo Mabuchi

We demonstrate a fast, robust and non-destructive protocol for quantum state estimation based on continuous weak measurement in the presence of a controlled dynamical evolution. Our experiment uses optically probed atomic spins as a…

Quantum Physics · Physics 2009-11-13 Greg A. Smith , Andrew Silberfarb , Ivan H. Deutsch , Poul S. Jessen

Von Neumann's statistical theory of quantum measurement interprets the instantaneous quantum state and derives instantaneous classical variables. In realty, quantum states and classical variables coexist and can influence each other in a…

Quantum Physics · Physics 2014-11-19 Lajos Diósi

We characterize the class of quantum measurements that matches the applications of quantum theory to cognition (and decision making) - quantum-like modeling. Projective measurements describe the canonical measurements of the basic…

Artificial Intelligence · Computer Science 2025-12-15 Miho Fuyama , Andrei Khrennikov , Masanao Ozawa

The Schr\"odinger-Newton equation aims at describing the dynamics of massive quantum systems subject to the gravitational self-interaction. As a deterministic nonlinear quantum wave equation, it is generally believed to conflict with the…

Quantum Physics · Physics 2025-12-23 Julia Osęka-Lenart , Marcin Płodzień , Maciej Lewenstein , Michał Eckstein

The paper deals with measures of nonlinearity. In state estimation, they are utilized i) to select a suitable state estimation algorithm by assessing the nonlinearity of a system model, ii) to adapt the estimation algorithm structure or…

Systems and Control · Electrical Eng. & Systems 2024-12-10 Ondřej Straka , Jindřich Havlík

An analysis of quantum measurement is presented that relies on an information-theoretic description of quantum entanglement. In a consistent quantum information theory of entanglement, entropies (uncertainties) conditional on measurement…

Quantum Physics · Physics 2008-02-03 N. J. Cerf , C. Adami

The quantum Zeno effect, in its original form, uses frequent projective measurements to freeze the evolution of a quantum system that is initially governed by a fixed Hamiltonian. We generalize this effect simultaneously in three directions…

Mathematical Physics · Physics 2021-04-09 Tim Möbus , Michael M. Wolf

We apply the Liouville-von Neumann (LvN) approach to open systems to describe the nonequilibrium quantum evolution. The Liouville-von Neumann approach is a unified method that can be applied to both time-independent (closed) and…

Statistical Mechanics · Physics 2016-08-31 Sang Pyo Kim

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

I flesh out the sense in which the informational approach to interpreting quantum mechanics, as defended by Pitowsky and Bub and lately by a number of other authors, is (neo-)Bohrian. I argue that on this approach, quantum mechanics…

Quantum Physics · Physics 2023-12-01 Michael E. Cuffaro