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The unitarity of quantum evolutions implies that the overlap between two initial states does not change in time. This property is commonly believed to explain the lack of state sensitivity in quantum theory, a feature that is prevailing in…

Quantum Physics · Physics 2021-12-01 Pawel Kurzynski

Investigated idea was actuated by the old opinion that a measurement of a quantum observable should be regarded a as a single deterministic sampling. But, according to the last decades studies, such observables are veritable random…

Quantum Physics · Physics 2012-11-20 Spiridon Dumitru

A diffusive stochastic Schr\"odinger equation (SSE) is shown for the first time, such that contributes to a non-completely positive dynamics. This contradicts to a recent Letter [arXiv:1303.4284] claiming that SSEs, under most general…

Quantum Physics · Physics 2014-11-19 Lajos Diósi

Is quantum mechanics about 'states'? Or is it basically another kind of probability theory? It is argued that the elementary formalism of quantum mechanics operates as a well-justified alternative to 'classical' instantiations of a…

Quantum Physics · Physics 2014-10-28 Jean-Michel Delhotel

Parameters of the mathematical model describing many practical dynamical systems are prone to vary due to aging or renewal, wear and tear, as well as changes in environmental or service conditions. These variabilities will adversely affect…

Systems and Control · Electrical Eng. & Systems 2022-07-13 Hang Geng , Mulugeta A. Haile , Huazhen Fang

Two thought experiments are analyzed, revealing that the quantum state of the universe does not contain definitive evidence of the wavefunction collapse. The first thought experiment shows that unitary quantum evolution alone can account…

Quantum Physics · Physics 2017-09-08 Ovidiu Cristinel Stoica

Spacetime must be foliable by spacelike surfaces for the quantum mechanics of matter fields to be formulated in terms of a unitarily evolving state vector defined on spacelike surfaces. When a spacetime cannot be foliated by spacelike…

General Relativity and Quantum Cosmology · Physics 2009-10-22 James B. Hartle

We propose a novel solution to the measurement problem based on quantum field theory and Haag's theorem. According to our proposal in elementary interactions where the particles content is changed, the temporal evolution is non unitary.…

Quantum Physics · Physics 2025-11-04 Avi Levy , Meir Hemmo

Recent results suggest that quantum mechanical phenomena may be interpreted as a failure of standard probability theory and may be described by a Bayesian complex probability theory.

Quantum Physics · Physics 2007-05-23 Saul Youssef

In conformal quantum mechanics with the vacuum of a real scaling dimension and with a complete orthonormal set of energy eigenstates which is preferable under the unitary evolution, the dilatation expectation value between energy…

High Energy Physics - Theory · Physics 2017-12-12 Tadashi Okazaki

In quantum mechanical experiments one distinguishes between the state of an experimental system and an observable measured in it. Heuristically, the distinction between states and observables is also suggested in scattering theory or when…

Quantum Physics · Physics 2015-05-20 Arno Bohm , Peter W. Bryant

Quantum measurements are described as instantaneous projections in textbooks. They can be stretched out in time using weak measurements, whereby one can observe the evolution of a quantum state as it heads towards one of the eigenstates of…

Quantum Physics · Physics 2018-04-11 Parveen Kumar , Suman Kundu , Madhavi Chand , R. Vijayaraghavan , Apoorva Patel

The usual conjectures of quantum measurements approaches, inspired from the traditional interpretation of Heisenberg's ("uncertainty") relations, are proved as being incorrect. A group of reconsidered conjectures and a corresponding new…

Quantum Physics · Physics 2007-05-23 Spiridon Dumitru

It has been proposed that measurement in quantum mechanics results from spontaneous breaking of a symmetry of the measuring apparatus and could be a unitary process that preserves coherence. Viewed in this manner, it is argued,…

Quantum Physics · Physics 2015-02-16 Partha Ghose

Experimentally observed violations of Bell inequalities rule out local realistic theories. Consequently, the quantum state vector becomes a strong candidate for providing an objective picture of reality. However, such an ontological view of…

Quantum Physics · Physics 2007-05-23 Bernd A. Berg

Realistic dynamical theories of measurement based on the diffusion of quantum states are nonunitary, whereas quantum field theory and its generalizations are unitary. This problem in the quantum field theory of quantum state diffusion (QSD)…

Quantum Physics · Physics 2009-10-31 Ian C. Percival

In this work we consider basic principles and problems of the standard quantum mechanical formalism. Especially we consider final measurement or detection procedure (collapse) as a quantum-classical continuous phase transition with…

Quantum Physics · Physics 2026-02-20 Vladan Pankovic

Starting with unitary quantum dynamics, we investigate how to add quantum measurements. Quantum measurements have four essential components: the furcation, the witness production, an alignment projection, and the actual choice decision. The…

Quantum Physics · Physics 2021-06-01 Fritz W. Bopp

Symmetry in mixed quantum states can manifest in two distinct forms: strong symmetry, where each individual pure state in the quantum ensemble is symmetric with the same charge, and weak symmetry, which applies only to the entire ensemble.…

Quantum Physics · Physics 2025-03-11 Leonardo A. Lessa , Ruochen Ma , Jian-Hao Zhang , Zhen Bi , Meng Cheng , Chong Wang

The mechanism of spontaneous symmetry breaking in quantum systems is briefly reviewed, rectifying part of the standard wisdom on logical and mathematical grounds. The crucial role of the localization properties of the time evolution for the…

History and Philosophy of Physics · Physics 2012-01-27 F. Strocchi