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Contextuality has been conjectured to be a super-classical resource for quantum computation, analogous to the role of non-locality as a super-classical resource for communication. We show that the presence of contextuality places a lower…

Quantum Physics · Physics 2018-02-23 Angela Karanjai , Joel J. Wallman , Stephen D. Bartlett

The classical causal relations between a set of variables, some observed and some latent, can induce both equality constraints (typically conditional independences) as well as inequality constraints (Instrumental and Bell inequalities being…

Quantum Physics · Physics 2024-04-11 Shashaank Khanna , Marina Maciel Ansanelli , Matthew F. Pusey , Elie Wolfe

Contextuality is considered as one of the most distinctive features of nonclassical systems. Here, we show that a Spekkens contextual system (which previous work has shown is a necessary condition for nonclassicality) formed of an…

Quantum Physics · Physics 2026-05-14 Enrico Bozzetto , Jonte R. Hance

The assumption of local realism in a Bell locality scenario imposes non-trivial conditions on the Shannon entropies of the associated probability distributions, expressed by linear entropic Bell inequalities. In principle, these entropic…

Quantum Physics · Physics 2013-06-24 Rafael Chaves

We show that Bell inequalities can be violated in the macroscopic world. The macroworld violation is illustrated using an example involving connected vessels of water. We show that whether the violation of inequalities occurs in the…

Quantum Physics · Physics 2022-10-12 Diederik Aerts , Sven Aerts , Jan Broekaert , Liane Gabora

Bell inequalities reveal the fundamentally nonlocal character of quantum mechanics. In this regard, one of the interesting problems is to explore all possible Bell inequalities that demonstrate a gap between local and nonlocal quantum…

Quantum Physics · Physics 2026-02-10 Palash Pandya , Shubhayan Sarkar , Remigiusz Augusiak

Reichenbach's principle states that in a causal structure, correlations of classical information can stem from a common cause in the common past or a direct influence from one of the events in correlation to the other. The difficulty of…

Quantum Physics · Physics 2018-06-19 Ämin Baumeler , Julien Degorre , Stefan Wolf

The problem of the existence of nonlocal effects in Quantum Mechanics is discussed. The problem is divided in two: the first ('soft') one is to explain the violation of Bell's inequalities as a statistical magnitude. This can be achieved by…

Quantum Physics · Physics 2026-03-11 Alejandro A. Hnilo

We present and experimentally demonstrate a novel non-classical phenomenon, bi-contextuality, observed in quantum systems prepared by two independent sources. This discovery plays a key role in the developing framework of network…

The derivation of Bell inequalities for beables is well-known to require a "no-conspiracy" assumption. This assumption is widely accepted, the alternative being correlations between instrument settings and hidden beables. Two further…

Quantum Physics · Physics 2007-05-23 Peter Morgan

In Phys. Rev. A 101, 022117 (2020), it was argued that Bell inequalities are based on classical, not quantum, physics, and hence their violation in experiments provides no support for the claimed existence of peculiar nonlocal and…

Quantum Physics · Physics 2022-01-03 Robert B. Griffiths

Recent experiments allowed concluding that Bell-type inequalities are indeed violated thus it is important to understand what it means and how can we explain the existence of strong correlations between outcomes of distant measurements. Do…

Quantum Physics · Physics 2017-12-05 Marian Kupczynski

A recent framework of quantum theory with no global causal order predicts the existence of "causally nonseparable" processes. Some of these processes produce correlations incompatible with any causal order (they violate so-called "causal…

Quantum Physics · Physics 2016-08-23 Adrien Feix , Mateus Araújo , Časlav Brukner

In the first part of this presentation (sections 2 to 6), I show that Bell's Inequalities provide a quantitative criterion to test "reasonable" Supplementary Parameters Theories versus Quantum Mechanics. Following Bell, I first explain the…

Quantum Physics · Physics 2007-05-23 Alain Aspect

Quantum contextuality represents a fundamental form of nonclassicality in quantum mechanics. To provide a more complete characterization of nonclassical properties in quantum systems, we adopt a logical perspective and propose a…

Quantum Physics · Physics 2025-12-03 Songyi Liu , Yongjun Wang , Baoshan Wang , Chang He , Jincheng Wang

Ilya Schmelzer wrote recently: {\it Nieuwenhuizen argued that there exists some "contextuality loophole" in Bell's theorem. This claim in unjustified}. It is made clear that this arose from attaching a meaning to the title and the content…

Quantum Physics · Physics 2017-09-28 Theodorus M. Nieuwenhuizen , Marian Kupczynski

Which nonlocal correlations can be obtained, when a party has access to more than one subsystem? While traditionally nonlocality deals with spacelike separated parties, this question becomes important with quantum technologies that connect…

Quantum Physics · Physics 2023-09-04 Moisés Bermejo Morán , Alejandro Pozas-Kerstjens , Felix Huber

Contextuality and measurement incompatibility are two fundamental aspects of nonclassicality, and their manifestations in observed quantum correlations are often deeply interconnected. Recently, measurement incompatibility has been studied…

Quantum Physics · Physics 2026-04-07 Swati Kumari , Sumit Mukherjee , R. Prabhu

From the modern perspective of causal inference, Bell's theorem -- a fundamental signature of quantum theory -- is a particular case where quantum correlations are incompatible with the classical theory of causality, and the generalization…

Quantum Physics · Physics 2024-05-30 Pedro Lauand , Bereket Ngussie Bekele , Elie Wolfe

It is well known that in quantum mechanics we cannot always define consistently properties that are context independent. Many approaches exist to describe contextual properties, such as Contextuality by Default (CbD), sheaf theory, topos…

Quantum Physics · Physics 2017-07-18 J. Acacio de Barros , Federico Holik , Decio Krause