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The relation between the restricted path integral approach to quantum measurement theory and the commonly accepted von Neumann wavefunction collapse postulate is presented. It is argued that in the limit of impulsive measurements the two…

Quantum Physics · Physics 2008-11-26 Tommaso Calarco

We develop the general quantum stochastic approach to the description of quantum measurements continuous in time. The framework, that we introduce, encompasses the various particular models for continuous-time measurements condsidered…

Quantum Physics · Physics 2007-05-23 Ole E. Barndorff-Nielsen , Elena R. Loubenets

Based on phase-space structures of quantum states, we propose a novel measure to quantify macroscopic quantum superpositions. Our measure simultaneously quantifies two different kinds of essential information for a given quantum state in a…

Quantum Physics · Physics 2011-06-02 Chang-Woo Lee , Hyunseok Jeong

We consider a quantum particle on a one dimensional lattice subject to weak local measurements and study its stochastic dynamics conditioned on the measurement outcomes. Depending on the measurement strength our analysis of the quantum…

Quantum Physics · Physics 2016-06-22 Ralf Blattmann , Klaus Mølmer

The aim of the article is to show how a coordinate transformation can be applied to the path-integral formalism. For this purpose the unitary definition of the quantum measure, which guarantees the conservation of total probability, is…

Quantum Physics · Physics 2007-05-23 J. Manjavidze

Quantum tunneling is a fundamental quantum mechanical effect involved in plenty of physical phenomena. Its control would impact these phenomena and the technologies based on them. We show that the quantum tunneling probability through a…

Quantum Physics · Physics 2022-08-17 Miguel A. Porras , Nilo Mata , Isabel Gonzalo

Quantum measurement is a fundamental cornerstone of experimental quantum computations. The main issues in current quantum measurement strategies are the high number of measurement rounds to determine a global optimal measurement output and…

Quantum Physics · Physics 2019-05-02 Laszlo Gyongyosi , Sandor Imre

It is straightforward to give a sum-over-paths expression for the transition amplitudes of a quantum circuit as long as the gates in the circuit are balanced, where to be balanced is to have all nonzero transition amplitudes of equal…

Quantum Physics · Physics 2017-08-15 Mark D. Penney , Dax Enshan Koh , Robert W. Spekkens

When measuring phase of quantum states of light, the optimal single-shot measurement implements projection on the un-physical phase states. If we want to improve the precision further we need to accept a reduced probability of success,…

Quantum Physics · Physics 2015-06-16 Petr Marek

A stochastic action principle for stochastic dynamics is revisited. We present first numerical diffusion experiments showing that the diffusion path probability depend exponentially on average Lagrangian action. This result is then used to…

Statistical Mechanics · Physics 2020-11-25 Q. A. Wang , F. Tsobnang , S. Bangoup , F. Dzangue , A. Jeatsa , A. Le Méhauté

In this paper, we present a thought experiment that demonstrates that the equivalence of quantum reduced states and statistical mixed states of ensembles is not merely a simple mathematical formulation in quantum mechanics, but rather…

Quantum Physics · Physics 2025-04-18 Zhihong Zuo

In the quantum Zeno effect, quantum measurements can block the coherent oscillation of a two level system by freezing its state to one of the measurement eigenstates. The effect is conventionally controlled by the measurement frequency.…

Quantum Physics · Physics 2020-10-06 Kyrylo Snizhko , Parveen Kumar , Alessandro Romito

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

Phase is a basic ingredient for quantum states since quantum mechanics uses complex numbers to describe quantum states. In this letter, we introduce a rigorous framework to quantify the phase of quantum states. To do so, we regard phase as…

Quantum Physics · Physics 2023-08-10 Jianwei Xu

The Einstein action for the gravitational field has some properties which make of it, after quantization, a rare prototype of systems with quantum configurations that do not have a classical analogue. Assuming spherical symmetry in order to…

General Relativity and Quantum Cosmology · Physics 2020-06-23 G. Modanese

A new idea for the quantization of dynamic systems, as well as space time itself, using a stochastic metric is proposed. The quantum mechanics of a mass point is constructed on a space time manifold using a stochastic metric. A stochastic…

General Relativity and Quantum Cosmology · Physics 2018-03-22 Yoshimasa Kurihara

A formalism for quantum many-body systems is proposed through a semiclassical treatment in phase space, allowing us to establish a stochastic thermodynamics incorporating quantum statistics. Specifically, we utilize a stochastic…

Statistical Mechanics · Physics 2024-12-23 Zhaoyu Fei

We predict that continuously monitored quantum dynamics can be chaotic. The optimal paths between past and future boundary conditions can diverge exponentially in time when there is time-dependent evolution and continuous weak monitoring.…

Quantum Physics · Physics 2018-08-08 Philippe Lewalle , John Steinmetz , Andrew N. Jordan

In many situations, one can approximate the behavior of a quantum system, i.e. a wave function subject to a partial differential equation, by effective classical equations which are ordinary differential equations. A general method and…

Mathematical Physics · Physics 2007-05-23 Martin Bojowald , Aureliano Skirzewski

Stochastic quantization in physics has been considered to provide a path integral representation of a probability distribution for Ito processes. It has been indicated that the stochastic quantization can involve a potential term, if the…

Systems and Control · Computer Science 2020-05-05 Masakazu Sano