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We propose a measure of non-Gaussianity for quantum states of a system of $n$ oscillator modes. Our measure is based on the quasi-probability $Q(\alpha), \alpha\in{\cal C}^n$. Since any measure of non-Gaussianity is necessarily an attempt…

Quantum Physics · Physics 2008-12-16 J. Solomon Ivan , M. Sanjay Kumar , R. Simon

To elucidate ideal measurements, one must explain how individual events emerge from quantum theory which deals with statistical ensembles, and how different may end up with different final states. This so-called "measurement problem" is…

Quantum Physics · Physics 2017-10-04 Armen E. Allahverdyan , Roger Balian , Theo M. Nieuwenhuizen

Measurement is of central interest in quantum mechanics as it provides the link between the quantum world and the world of everyday experience. One of the features of the latter is its robust, objective character, contrasting the delicate…

Quantum Physics · Physics 2017-12-19 J. K. Korbicz , E. A. Aguilar , P. Ćwikliński , P. Horodecki

In a previous paper, the author proposed a quantum mechanical interaction that would insure that the evolution of subjective states would parallel the evolution of biological states, as required by von Neumann's theory of measurement. The…

Quantum Physics · Physics 2007-05-23 Richard A. Mould

We show that the so-called quantum probabilistic rule, usually presented in the physical literature as an argument of the essential distinction between the probability relations under quantum and classical measurements, is not, as it is…

Quantum Physics · Physics 2019-11-19 Andrei Khrennikov , Elena Loubenets

Measurement is a fundamental notion in the usual approximate quantum mechanics of measured subsystems. Probabilities are predicted for the outcomes of measurements. State vectors evolve unitarily in between measurements and by reduction of…

General Relativity and Quantum Cosmology · Physics 2014-01-14 James B. Hartle

A novel solution to the quantum measurement problem is presented by using a new asymmetric equation that is complementary to the Schr\"odinger equation. Solved for the hydrogen atom, the new equation describes the temporal and spatial…

General Physics · Physics 2024-10-25 Z. E. Musielak

In this note, we give an overview of some results obtained in [3]. This latter work is devoted to the study of the one-dimensional nonlinear Schr{\"o}dinger equation with random initial conditions. Namely, we describe the nonlinear…

Analysis of PDEs · Mathematics 2024-04-05 Laurent Thomann , Nicolas Burq

A recent result about measurability of a quantum state of a single quantum system is generalized to the case of a single pre- and post-selected quantum system described by a two-state vector. The protection required for such measurement is…

Quantum Physics · Physics 2007-05-23 Y. Aharonov , L. Vaidman

Nonlinear interactions are recognized as potential resources for quantum metrology, facilitating parameter estimation precisions that scale as the exponential Heisenberg limit of $2^{-N}$. We explore such nonlinearity and propose an…

A new quantum correlation in terms of the average distance between the reduced state and the $i$-th output reduced states under local von Neumann measurements is proposed. It is shown that only the product states do not contain this quantum…

Quantum Physics · Physics 2015-05-12 Yu Guo , Xiulan Li , Bo Li , Heng Fan

The Kochen-Specker theorem rules out models of quantum theory wherein projective measurements are assigned outcomes deterministically and independently of context. This notion of noncontextuality is not applicable to experimental…

Quantum Physics · Physics 2018-05-11 Ravi Kunjwal , Robert W. Spekkens

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

We analyze general enough models of repeated indirect measurements in which a quantum system interacts repeatedly with randomly chosen probes on which Von Neumann direct measurements are performed. We prove, under suitable hypotheses, that…

Mathematical Physics · Physics 2015-06-05 Michel Bauer , Tristan Benoist , Denis Bernard

Recently, [arXiv:0810.3134] is accepted and published. We derive an inequality with two settings as tests for the existence of the Bloch sphere in a spin-1/2 system. The probability theory of measurement outcome within the formalism of von…

General Physics · Physics 2008-11-28 Koji Nagata

We report the results of an experiment that searches for causal non-linear state-dependent terms in quantum field theory. Our approach correlates a binary macroscopic classical voltage with the outcome of a projective measurement of a…

We report the first implementation of the von Neumann instantaneous measurements of nonlocal variables which becomes possible due to technological achievements in creating hyperentangled photons. Tests of reliability and of the…

In this work we analyze a non-commutativity measure of quantum correlations recently proposed by Y. Guo [Sci. Rep. 6, 25241 (2016)]. By recourse to a systematic survey of a two-qubit system, we detected an undesirable behavior of such a…

Quantum Physics · Physics 2017-08-25 A. P. Majtey , D. Bussandri , T. M. Osán , P. W. Lamberti , A. Valdés-Hernández

The Schrodinger equation is incomplete, inherently unable to explain the collapse of the wavefunction caused by measurement; a fundamental issue known as the quantum measurement problem. Quantum mechanics is generally constrained by the…

Quantum Physics · Physics 2024-12-19 Kyoung Yeon Kim

A gauge-invariant Wigner quantum mechanical theory is obtained by applying the Weyl-Stratonovich transform to the von Neumann equation for the density matrix. The transform reduces to the Weyl transform in the electrostatic limit, when the…

Mathematical Physics · Physics 2022-11-24 Mihail Nedjalkov , Mauro Ballicchia , Robert Kosik , Josef Weinbub