scholarly journals Bell nonlocality in networks

2021 ◽  
Author(s):  
Armin Tavakoli ◽  
Alejandro Pozas-Kerstjens ◽  
mingxing luo ◽  
Marc-Olivier Renou
Keyword(s):  
Quantum Theory ◽  
Information Science ◽  
Physical Models ◽  
Bell’S Theorem ◽  
Bell's Theorem ◽  
Physical Systems ◽  
Future Challenges ◽  
Practical Challenge ◽  
Einstein Podolsky Rosen ◽  
Bell Nonlocality

Abstract Bell’s theorem proves that quantum theory is inconsistent with local physical models. It has propelled research in the foundations of quantum theory and quantum information science. As a fundamental feature of quantum theory, it impacts predictions far beyond the traditional scenario of the Einstein-Podolsky-Rosen paradox. In the last decade, the investigation of nonlocality has moved beyond Bell’s theorem to consider more sophisticated experiments that involve several independent sources that distribute shares of physical systems among many parties in a network. Network scenarios, and the nonlocal correlations that they give rise to, lead to phenomena that have no counterpart in traditional Bell experiments, thus presenting a formidable conceptual and practical challenge. This review discusses the main concepts, methods, results and future challenges in the emerging topic of Bell nonlocality in networks.

Bell’s theorem

2018 ◽  
Author(s):  
Arthur Fine
Keyword(s):  
Quantum Mechanics ◽  
Quantum Theory ◽  
Experimental Tests ◽  
Bell Inequalities ◽  
Bell’S Theorem ◽  
Bell's Theorem ◽  
Bell Theorem ◽  
System Of Inequalities ◽  
Action At A Distance ◽  
High Degree

Bell’s theorem is concerned with the outcomes of a special type of ‘correlation experiment’ in quantum mechanics. It shows that under certain conditions these outcomes would be restricted by a system of inequalities (the ‘Bell inequalities’) that contradict the predictions of quantum mechanics. Various experimental tests confirm the quantum predictions to a high degree and hence violate the Bell inequalities. Although these tests contain loopholes due to experimental inefficiencies, they do suggest that the assumptions behind the Bell inequalities are incompatible not only with quantum theory but also with nature. A central assumption used to derive the Bell inequalities is a species of no-action-at-a-distance, called ‘locality’: roughly, that the outcomes in one wing of the experiment cannot immediately be affected by measurements performed in another wing (spatially distant from the first). For this reason the Bell theorem is sometimes cited as showing that locality is incompatible with the quantum theory, and the experimental tests as demonstrating that nature is nonlocal. These claims have been contested.

scholarly journals Nonlocality in Bell’s Theorem, in Bohm’s Theory, and in Many Interacting Worlds Theorising

Entropy ◽  
2018 ◽  
Vol 20 (8) ◽  
pp. 567 ◽  
Author(s):  
Mojtaba Ghadimi ◽  
Michael Hall ◽  
Howard Wiseman
Keyword(s):  
Quantum Mechanics ◽  
Quantum Theory ◽  
Bohmian Mechanics ◽  
Bell’S Theorem ◽  
Bell's Theorem ◽  
Significant Progress ◽  
Technical Problems ◽  
New Approach ◽  
Weak Notion ◽  
Bohm’S Theory

“Locality” is a fraught word, even within the restricted context of Bell’s theorem. As one of us has argued elsewhere, that is partly because Bell himself used the word with different meanings at different stages in his career. The original, weaker, meaning for locality was in his 1964 theorem: that the choice of setting by one party could never affect the outcome of a measurement performed by a distant second party. The epitome of a quantum theory violating this weak notion of locality (and hence exhibiting a strong form of nonlocality) is Bohmian mechanics. Recently, a new approach to quantum mechanics, inspired by Bohmian mechanics, has been proposed: Many Interacting Worlds. While it is conceptually clear how the interaction between worlds can enable this strong nonlocality, technical problems in the theory have thus far prevented a proof by simulation. Here we report significant progress in tackling one of the most basic difficulties that needs to be overcome: correctly modelling wavefunctions with nodes.

scholarly journals The Hardy’s nonlocality argument

2016 ◽  
Vol 14 (06) ◽  
pp. 1640035
Author(s):  
Sujit K Choudhary ◽  
Pankaj Agrawal
Keyword(s):  
Quantum Theory ◽  
Bell’S Theorem ◽  
Local Realism ◽  
Bell’S Inequality ◽  
Bell's Theorem ◽  
Famous Theorem ◽  
Bell's Inequality

Certain predictions of quantum theory are not compatible with the notion of local-realism. This was the content of Bell’s famous theorem of the year 1964. Bell proved this with the help of an inequality, famously known as Bell’s inequality. The alternative proofs of Bell’s theorem without using Bell’s inequality are known as “nonlocality without inequality (NLWI)” proofs. We review one such proof namely the Hardy’s proof which due to its simplicity and generality has been considered the best version of Bell’s theorem.

scholarly journals Bell’s “Theorem”: loopholes vs. conceptual flaws

Open Physics ◽  
2017 ◽  
Vol 15 (1) ◽  
pp. 754-761
Author(s):  
A. F. Kracklauer
Keyword(s):  
Quantum Theory ◽  
Critical Analysis ◽  
Current Theory ◽  
Central Point ◽  
Bell’S Theorem ◽  
Historical Overview ◽  
Bell's Theorem ◽  
Conditional Probabilities

AbstractAn historical overview and detailed explication of a critical analysis of what has become known as Bell’s Theorem to the effect that, it should be impossible to extend Quantum Theory with the addition of local, real variables so as to obtain a version free of the ambiguous and preternatural features of the currently accepted interpretations is presented. The central point on which this critical analysis, due originally to Edwin Jaynes, is that Bell incorrectly applied probabilistic formulas involving conditional probabilities. In addition, mathematical technicalities that have complicated the understanding of the logical or mathematical setting in which current theory and experimentation are embedded, are discussed. Finally, some historical speculations on the sociological environment, in particular misleading aspects, in which recent generations of physicists lived and worked are mentioned.

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