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Weak measurement is a standard measuring procedure with two changes: it is performed on pre- and post-selected quantum systems and the coupling to the measuring device is weakened. The outcomes of weak measurements, ``weak values'' are very…

High Energy Physics - Theory · Physics 2009-09-25 Lev Vaidman

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

In this contribution I review rigorous formulations of a variety of limitations of measurability in quantum mechanics. To this end I begin with a brief presentation of the conceptual tools of modern measurement theory. I will make precise…

Quantum Physics · Physics 2011-01-04 Paul Busch

The uncertainty relation, as one of the fundamental principles of quantum physics, captures the incompatibility of noncommuting observables in the preparation of quantum states. In this work, we derive two strong and universal uncertainty…

Quantum Physics · Physics 2019-04-10 Zhi-Xin Chen , Hui Wang , Jun-Li Li , Qiu-Cheng Song , Cong-Feng Qiao

We combine traditional pointer-based simultaneous measurements of conjugate observables with the concept of quantum Brownian motion of multipartite systems to phenomenologically model simultaneous measurements of conjugate observables in a…

Quantum Physics · Physics 2014-05-14 Raoul Heese , Matthias Freyberger

We establish a framework for the study of the effective theory of weak convergence of measures. We define two effective notions of weak convergence of measures on $\mathbb{R}$: one uniform and one non-uniform. We show that these notions are…

Logic · Mathematics 2021-06-03 Timothy H. McNicholl , Diego A. Rojas

The relation between quantum measurement and thermodynamically irreversible processes is investigated. The reduction of the state vector is fundamentally asymmetric in time and shows an observer-relatedness which may explain the double…

Quantum Physics · Physics 2015-06-26 H. D. Zeh

Heisenberg's uncertainty principle is one of the main tenets of quantum theory. Nevertheless, and despite its fundamental importance for our understanding of quantum foundations, there has been some confusion in its interpretation: although…

Quantum Physics · Physics 2013-05-06 Cyril Branciard

We reconsider a well known problem of quantum theory, i.e. the so called measurement (or macro-objectification) problem, and we rederive the fact that it gives rise to serious problems of interpretation. The novelty of our approach derives…

Quantum Physics · Physics 2009-11-06 Angelo Bassi , GianCarlo Ghirardi

In contrast to a projective quantum measurement in which the system is projected onto an eigenstate of the measured operator, in a weak measurement the system is only weakly perturbed while only partial information on the measured…

Quantum Physics · Physics 2018-10-26 Maicol A. Ochoa , Wolfgang Belzig , Abraham Nitzan

We introduce contextual values as a generalization of the eigenvalues of an observable that takes into account both the system observable and a general measurement procedure. This technique leads to a natural definition of a general…

Quantum Physics · Physics 2010-06-16 J. Dressel , S. Agarwal , A. N. Jordan

Precise definitions of "weak [quantum] measurements" and "weak value" [of a quantum observable] are offered, which seem to capture the meaning of the often vague ways that these terms are used in the literature. Simple finite dimensional…

Quantum Physics · Physics 2010-01-11 Stephen Parrott

We conjecture new uncertainty relations which restrict correlations between results of measurements performed by two separated parties on a shared quantum state. The first uncertainty relation bounds the sum of two mutual informations when…

It is shown that the joint measurements of some physical variables corresponding to commuting operators performed on pre- and post-selected quantum systems invariably disturb each other. The significance of this result for recent proofs of…

High Energy Physics - Theory · Physics 2009-10-22 Lev Vaidman

Three recent results on weak measurements are presented. They are: i) repeated measurements on a single copy can not provide any information on it and further, that in the limit of very large such measurements, weak measurements have…

Quantum Physics · Physics 2015-09-17 N. D. Hari Dass

For any pair of bounded observables $A$ and $B$ with pure point spectra, we construct an associated "joint observable" which gives rise to a notion of a joint (projective) measurement of $A$ and $B$, and which conforms to the intuition that…

Quantum Physics · Physics 2015-06-22 Richard DeJonghe , Kimberly Frey , Tom Imbo

Measurement incompatibility stipulates the existence of quantum measurements that cannot be carried out simultaneously on single systems. We show that the set of input-output probabilities obtained from d-dimensional classical systems…

Quantum Physics · Physics 2023-06-13 Debashis Saha , Debarshi Das , Arun Kumar Das , Bihalan Bhattacharya , A. S. Majumdar

The evaluation of uncertainties in quantum measurements is problematic since the correct value of an observable between state preparation and measurement is experimentally inaccessible. In Ozawa's formulation of uncertainty relations for…

Quantum Physics · Physics 2012-05-02 Holger F. Hofmann

We introduce a new way of quantifying the degrees of incompatibility of two ob- servables in a probabilistic physical theory and, based on this, a global measure of the degree of incompatibility inherent in such theories, across all…

Quantum Physics · Physics 2013-08-23 Paul Busch , Teiko Heinosaari , Jussi Schultz , Neil Stevens

In the first part of this two-part article, we have introduced and analyzed a multidimensional model, called the 'general tension-reduction' (GTR) model, able to describe general quantum-like measurements with an arbitrary number of…

Quantum Physics · Physics 2015-09-17 Diederik Aerts , Massimiliano Sassoli de Bianchi