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The problem of measurement in quantum mechanics is reanalyzed within a general, strictly probabilistic framework (without reduction postulate). Based on a novel comprehensive definition of measurement the natural emergence of objective…

Quantum Physics · Physics 2007-05-23 Markus Simonius

Quantum measurement is a physical process. What physical resources and constraints does quantum mechanics require for measurement to produce the classical world we observe? Treating measurement as a fully unitary quantum process, our goal…

Quantum Physics · Physics 2025-12-09 Vishal Johnson , Ashmeet Singh , Reimar Leike , Philipp Frank , Torsten Enßlin

Multipartite entanglement is an essential resource for quantum communication, quantum computing, quantum sensing, and quantum networks. The utility of a quantum state, $|\psi\rangle$, for these applications is often directly related to the…

Quantum Physics · Physics 2022-01-05 Jacob L. Beckey , N. Gigena , Patrick J. Coles , M. Cerezo

The existence of incompatible measurements, i.e. measurements which cannot be performed simultaneously on a single copy of a quantum state, constitutes an important distinction between quantum mechanics and classical theories. While…

Quantum Physics · Physics 2022-06-22 Krzysztof Mordasewicz , Jędrzej Kaniewski

We point out that a quantum system with a strongly positive quantum measure or decoherence functional gives rise to a vector valued measure whose domain is the algebra of events or physical questions. This gives an immediate handle on the…

General Relativity and Quantum Cosmology · Physics 2010-11-30 Fay Dowker , Steven Johnston , Sumati Surya

The expected indefinite causal structure in quantum gravity poses a challenge to the notion of entanglement: If two parties are in an indefinite causal relation of being spacelike and timelike, can they still be entangled? If so, how does…

Quantum Physics · Physics 2018-02-27 Ding Jia

We present two sets of computable entanglement measures for multipartite systems where each subsystem can have different degrees of freedom (so-called qudits). One set, called 'separability' measure, reveals which of the subsystems are…

Quantum Physics · Physics 2009-06-10 Beatrix C. Hiesmayr , Marcus Huber , Philipp Krammer

The certification of Bell nonlocality or quantum steering implies the use of incompatible measurements. Here we make this connection quantitative. We show how to strengthen robustness-based steering and nonlocality quantifiers in order that…

Quantum Physics · Physics 2016-06-07 Daniel Cavalcanti , Paul Skrzypczyk

The theory of generalised measurements is used to examine the problem of discriminating unambiguously between non-orthogonal pure quantum states. Measurements of this type never give erroneous results, although, in general, there will be a…

Quantum Physics · Physics 2009-10-31 Anthony Chefles

Understanding the influence of measurements on the properties of many-body systems is a fundamental problem in quantum mechanics and for quantum technologies. This paper explores how a finite density of stochastic local measurement modifies…

Quantum Physics · Physics 2024-12-25 Alessio Paviglianiti , Xhek Turkeshi , Marco Schirò , Alessandro Silva

The parameterized entanglement monotone, the $q$-concurrence, is also a reasonable parameterized entanglement measure. By exploring the properties of the $q$-concurrence with respect to the positive partial transposition and realignment of…

Quantum Physics · Physics 2022-06-17 Zhi-Wei Wei , Ming-Xing Luo , Shao-Ming Fei

Joint measurements of non-commuting observables are characterized by unavoidable measurement uncertainties that can be described in terms of the error statistics for input states with well-defined values for the target observables. However,…

Quantum Physics · Physics 2015-10-28 Shota Kino , Taiki Nii , Holger F. Hofmann

Theory of quantum measurements is often classified as decision theory. An event in decision theory corresponds to the measurement of an observable. This analogy looks clear for operationally testable simple events. However, the situation is…

Quantum Physics · Physics 2015-06-24 V. I. Yukalov , D. Sornette

Measurements performed on distant parts of an entangled quantum state can generate correlations incompatible with classical theories respecting the assumption of local causality. This is the phenomenon known as quantum non-locality that,…

Quantum Physics · Physics 2018-02-28 S. G. A. Brito , B. Amaral , R. Chaves

A pedagogical and reasonably self-contained introduction to the measurement problems in quantum mechanics and their partial solution by environment-induced decoherence (plus some other important aspects of dcoherence) is given. The point…

Quantum Physics · Physics 2007-05-23 Tulsi Dass

Local measurements cannot create entanglement, but they can convert short-range entanglement to long-range entanglement, as in quantum teleportation. This phenomenon of measurement-induced entanglement (MIE) has been widely discussed in…

Quantum Physics · Physics 2024-10-10 Yifan Zhang , Sarang Gopalakrishnan

The aim of this paper is to extend the concept of measure density introduced by Buck for finite unions of arithmetic progressions, to arbitrary subsets of N defined by a given system of decompositions. This leads to a variety of new…

Classical Analysis and ODEs · Mathematics 2015-04-10 Maria Rita Iacò , Milan Paštéka , Robert F. Tichy

We discuss on general grounds some local indicators of entanglement, that have been proposed recently for the study and classification of quantum phase transitions. In particular, we focus on the capability of entanglement in detecting…

Quantum Physics · Physics 2007-05-23 L. Campos Venuti , C. Degli Esposti Boschi , G. Morandi , M. Roncaglia , A. Scaramucci

The concept of quantization consists in replacing commutative quantities by noncommutative ones. In mathematical language an algebra of continuous functions on a locally compact topological space is replaced with a noncommutative…

Operator Algebras · Mathematics 2018-02-13 Petr Ivankov

We provide an interpretation of entanglement based on classical correlations between measurement outcomes of complementary properties: states that have correlations beyond a certain threshold are entangled. The reverse is not true, however.…

Quantum Physics · Physics 2015-05-26 Lorenzo Maccone , Dagmar Bruss , Chiara Macchiavello