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Quantum mechanics permits nonlocality - both nonlocal correlations and nonlocal equations of motion - while respecting relativistic causality. Is quantum mechanics the unique theory that reconciles nonlocality and causality? We consider two…

Quantum Physics · Physics 2008-02-03 Sandu Popescu , Daniel Rohrlich

Non-locality without entanglement is a rather counter-intuitive phenomenon in which information may be encoded entirely in product (unentangled) states of composite quantum systems in such a way that local measurement of the subsystems is…

Quantum Physics · Physics 2017-03-08 Sarah Croke , Stephen M Barnett

The principle of tomographic locality states that the operational state of a multipartite system can be fully characterized by the statistics obtained from measurements that are local to the individual subsystems. This property holds in…

Quantum Physics · Physics 2025-06-10 Tristan S. Lismer , Kaleb B. Felefele , Robert W. Spekkens , Kevin J. Resch

In the present paper, we attempt to address the question of "can tensorizing states have quantum advantages?". To answer this question, we exploit the notion of measurement-induced nonlocality (MIN) and advocate a fidelity based nonbilocal…

Quantum Physics · Physics 2023-01-20 S. Bhuvaneswari , R. Muthuganesan , R. Radha

The outcomes of measurements on entangled quantum systems can be nonlocally correlated. However, while it is easy to write down toy theories allowing arbitrary nonlocal correlations, those allowed in quantum mechanics are limited. Quantum…

Quantum Physics · Physics 2015-03-17 Peter Janotta , Christian Gogolin , Jonathan Barrett , Nicolas Brunner

The Bell nonlocality is closely related to the foundations of quantum physics and has significant applications to security questions in quantum key distributions. In recent years, the sharing ability of the Bell nonlocality has been…

Quantum Physics · Physics 2023-02-22 Tinggui Zhang , Naihuan Jing , Shao-Ming Fei

In a recent note, Hance and Hossenfelder (arXiv:2211.01331) recall that "locally causal completions of quantum mechanics are possible, if they violate the assumption [called statistical independence or measurement independence] that the…

Quantum Physics · Physics 2022-11-15 Adán Cabello

Two central concepts of quantum mechanics are Heisenberg's uncertainty principle, and a subtle form of non-locality that Einstein famously called ``spooky action at a distance''. These two fundamental features have thus far been distinct…

Quantum Physics · Physics 2010-11-22 Jonathan Oppenheim , Stephanie Wehner

This article presents a local realistic interpretation of quantum entanglement. The entanglement is explained as innate interference between the non-empty state associated with the peaked piece of one particle and the empty states…

Quantum Physics · Physics 2007-05-23 Wang Guowen

Measurements on entangled quantum states can produce outcomes that are nonlocally correlated. But according to Tsirelson's theorem, there is a quantitative limit on quantum nonlocality. It is interesting to explore what would happen if…

Quantum Physics · Physics 2010-04-14 Anthony J. Short , Jonathan Barrett

It is argued that the quantum correlations are not maximally nonlocal to make it possible to control local outcomes from outside spacetime, and quantum mechanics emerges from timeless nonlocality and biased local randomness. This rules out…

Quantum Physics · Physics 2009-02-17 Antoine Suarez

In order to understand whether nonlocality implies information transfer, a quantum optical experimental test, well within the scope of current technology, is proposed. It is essentially a delayed choice experiment as applied to entangled…

Quantum Physics · Physics 2007-05-23 R. Srikanth

A general method for extending a non-dissipative nonlinear Schr\"odinger and Liouville-von Neumann 1-particle dynamics to an arbitrary number of particles is described. It is shown at a general level that the dynamics so obtained is…

Quantum Physics · Physics 2009-10-30 Marek Czachor

We introduce a generalization of the set of completely positive matrices that we call "pairwise completely positive" (PCP) matrices. These are pairs of matrices that share a joint decomposition so that one of them is necessarily positive…

Quantum Physics · Physics 2019-05-30 Nathaniel Johnston , Olivia MacLean

We discuss the (re-)construction of quasiprobability representations from generic measurements, including noisy ones. Based on the measurement under study, quasiprobabilities and the associated concept of nonclassicality are introduced. A…

Quantum Physics · Physics 2025-11-07 Jan Sperling , Laura Ares , Elizabeth Agudelo

One of the fundamental questions in physics concerns the relation between spacetime and quantum entanglement. The spacetime is usually considered as a fixed background physical space, and the quantum entanglement is usually manifested as a…

Quantum Physics · Physics 2026-03-10 Akbar Fahmi

Nonlocality is arguably one of the most fundamental and counterintuitive aspects of quantum theory. Nonlocal correlations could, however, be even more nonlocal than quantum theory allows, while still complying with basic physical principles…

Quantum Physics · Physics 2014-03-17 A. B. Sainz , T. Fritz , R. Augusiak , J. Bohr Brask , R. Chaves , A. Leverrier , A. Acín

Recently, the quantumness of local correlations arising from separable states in the context of a Bell scenario has been studied and linked with superlocality [Phys. Rev. A {\bf 95}, 032120 (2017)]. Here we investigate the quantumness of…

Nonlocality and entanglement are not only the fundamental characteristics of quantum mechanics but also important resources for quantum information and computation applications. Exploiting the quantitative relationship between the two…

Quantum Physics · Physics 2020-04-20 Zhaofeng Su , Haisheng Tan , Xiangyang Li

We represent a two-qubit density matrix in the basis of Pauli matrix tensor products, with the coefficients constituting a Bloch matrix, analogous to the single qubit Bloch vector. We find the quantum state positivity requirements on the…

Quantum Physics · Physics 2016-11-27 Omar Gamel