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We develop a dynamical framework for quantum measurement based on stochastic but unitary evolution in projective state space. Random Hamiltonians drawn from the Gaussian Unitary Ensemble generate stochastic unitary dynamics of the quantum…

Quantum Physics · Physics 2026-01-27 Alexey A. Kryukov

We analyze the non-Markovian stochastic Schroedinger equation describing a particle subject to spontaneous collapses in space (in the language of collapse models), or subject to a continuous measurement of its position (in the language of…

Quantum Physics · Physics 2009-07-30 Angelo Bassi , Luca Ferialdi

Following the reasoning of Claudson and Halpern, it is shown that "fifth-time" stabilized quantum gravity is equivalent to Langevin evolution (i.e. stochastic quantization) between fixed non-singular, but otherwise arbitrary, initial and…

High Energy Physics - Theory · Physics 2009-10-22 J. Greensite

We give an explicit stochastic Hamiltonian model of discontinuous unitary evolution for quantum spontaneous jumps like in a system of atoms in quantum optics, or in a system of quantum particles that interacts singularly with "bubbles"…

Quantum Physics · Physics 2009-11-11 V. P. Belavkin , O. Melsheimer

Collapse of the wave function appears to violate the quantum superposition principle as well as deterministic evolution. Objective collapse models propose a dynamical explanation for this phenomenon, by making a stochastic non-unitary and…

Quantum Physics · Physics 2023-10-27 Kartik Kakade , Avnish Singh , Tejinder P. Singh

It is shown that the classical book by von Neumann proposing dynamics of measured systems with "reduction (or collapse) of system's wave packet" contains also hints how to avoid this discontinuity in time evolution of the measured system…

Quantum Physics · Physics 2022-01-12 Pavel Bóna

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

The basic strategy underlying models of spontaneous wave function collapse (collapse models) is to modify the Schroedinger equation by including nonlinear stochastic terms, which tend to localize wave functions in space in a dynamical…

Quantum Physics · Physics 2015-06-18 A. Bassi , H. Ulbricht

Stochastic unravelings provide a useful way to represent open quantum system dynamics in terms of pure state realizations, and have been widely studied both from a fundamental and from a computational point of view. They were initially…

Quantum Physics · Physics 2026-05-11 Federico Settimo , Jyrki Piilo

We explore, both analytically and numerically, the quantum dynamics of a many-body free-fermion system subjected to local density measurements. We begin by extending the mapping to the nonlinear sigma-model (NLSM) field theory for the case…

Disordered Systems and Neural Networks · Physics 2026-04-22 Igor Poboiko , Alexander D. Mirlin

This paper presents a new modified quantum mechanics, Critical Complexity Quantum Mechanics, which includes a new account of wavefunction collapse. This modified quantum mechanics is shown to arise naturally from a fully discrete physics,…

Quantum Physics · Physics 2016-04-26 Martin Leckey

The lack of superposition of different position states or the emergence of classicality in macroscopic systems have been a puzzle for decades. Classicality exists in every measuring apparatus, and is the key for understanding what can be…

Quantum Physics · Physics 2020-12-08 Pei Wang

The dynamical equation of hybrid systems, being the combination of Schr\"odinger and Liouville equations, produces noncausal evolution when the initial state of interacting quantum and classical mechanical systems is as it is demanded in…

Quantum Physics · Physics 2007-05-23 Slobodan Prvanovic

We show using a realistic Hamiltonian-type model that definite outcomes of quantum measurements may emerge from quantum evolution of pure states, i.e quantum dynamics provides a deterministic collapse of the wavefunction in a quantum…

Quantum Physics · Physics 2008-09-10 Håkon Brox , Kåre Olaussen , Anh Kiet Nguyen

Dynamical reduction models propose a solution to the measurement problem in quantum mechanics: the collapse of the wave function becomes a physical process. We compute the predictions to decaying and Dynamical reduction models propose a…

Quantum Physics · Physics 2016-12-01 K. Simonov , B. C. Hiesmayr

We develop an interacting extension of the Double Covariance Model (DCM), a stochastic subquantum framework in which macroscopic quantum dynamics emerge through coarse-graining of correlated microscopic fluctuations. Starting from local…

Quantum Physics · Physics 2026-05-29 Andrei Khrennikov

We propose a system of equations to describe the interaction of a quasiclassical variable $X$ with a set of quantum variables $x$ that goes beyond the usual mean field approximation. The idea is to regard the quantum system as continuously…

Quantum Physics · Physics 2009-10-30 L. Diosi , J. J. Halliwell

It is well-known that quantum mechanics admits two distinct evolutions: the unitary evolution, which is deterministic and well described by the Schr\"{o}dinger equation, and the collapse of the wave function, which is probablistic,…

Quantum Physics · Physics 2026-04-07 Le Hu , Andrew N. Jordan

This paper studies the Kalman decomposition for linear quantum systems. Contrary to the classical case, the coordinate transformation used for the decomposition must belong to a specific class of transformations as a consequence of the laws…

Quantum Physics · Physics 2017-06-13 Guofeng Zhang , Symeon Grivopoulos , Ian R. Petersen , John E. Gough

We investigate what a snapshot of a quantum evolution - a quantum channel reflecting open system dynamics - reveals about the underlying continuous time evolution. Remarkably, from such a snapshot, and without imposing additional…

Quantum Physics · Physics 2009-11-13 M. M. Wolf , J. Eisert , T. S. Cubitt , J. I. Cirac