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In quantum physics the term `contextual' can be used in more than one way. One usage, here called `Bell contextual' since the idea goes back to Bell, is that if $A$, $B$ and $C$ are three quantum observables, with $A$ compatible (i.e.,…

Quantum Physics · Physics 2019-09-19 Robert B. Griffiths

Phase space quasi-probability functions provide powerful representations of quantum states and operators, as well as criteria for assessing quantum computational resources. In discrete, odd-dimensional systems (qudits), protocols involving…

Quantum Physics · Physics 2025-12-08 Eloi Descamps , Astghik Saharyan , Arne Keller , Pérola Milman

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

By analyzing the concept of contextuality (Bell-Kochen-Specker) in terms of pre-and-post-selection (PPS), it is possible to assign definite values to observables in a new and surprising way. Physical reasons are presented for restrictions…

Quantum Physics · Physics 2009-11-13 Jeff Tollaksen

Contextuality is a key distinguishing feature between classical and quantum physics. It expresses a fundamental obstruction to describing quantum theory using classical concepts. In turn, when understood as a resource for quantum…

Quantum Physics · Physics 2025-01-17 Markus Frembs

Bell inequalities play a central role in the study of quantum non-locality and entanglement, with many applications in quantum information. Despite the huge literature on Bell inequalities, it is not easy to find a clear conceptual answer…

Quantum Physics · Physics 2012-06-21 Samson Abramsky , Lucien Hardy

Contextuality is a key signature of quantum non-classicality, which has been shown to play a central role in enabling quantum advantage for a wide range of information-processing and computational tasks. We study the logic of contextuality…

Quantum Physics · Physics 2021-03-09 Samson Abramsky , Rui Soares Barbosa

Description of nonclassicality of states has hitherto been through violation of Bell inequality and non-separability, with the latter being a stronger constraint. In this paper, we show that this can be further sharpened, by introducing the…

Quantum Physics · Physics 2015-06-18 H. M. Bharath , V. Ravishankar

Contextuality lays at the heart of quantum mechanics. In the prevailing opinion it is considered as a signature of 'quantumness' that classical theories lack. However, this assertion is only partially justified. Although contextuality is…

Quantum Physics · Physics 2015-02-26 Pawel Blasiak

(A) The momentum density conjugate to a bosonic quantum field splits naturally into the sum of a classical component and a nonclassical component. It is shown that the field and the nonclassical component of the momentum density satisfy…

High Energy Physics - Theory · Physics 2007-05-23 Michael J. W. Hall , Kailash Kumar , Marcel Reginatto

This article delves into the concept of quantum contextuality, specifically focusing on proofs of the Kochen-Specker theorem obtained by assigning Pauli observables to hypergraph vertices satisfying a given commutation relation. The…

Quantum Physics · Physics 2025-08-27 Axel Muller , Alain Giorgetti

Within the Dempster-Schafer theory of evidence a non-Kolmogorovian kind of epistemic uncertainty arises, which is encoded using multi-valued maps. We analyse the possible implications such non-Kolmogorovian epistemic uncertainty may have…

Quantum Physics · Physics 2015-06-09 Adam Stokes

Bell scenarios are multipartite scenarios that exclude any signalling between parties. This leads to a strict hierarchy of classical, quantum, and non-signalling correlations in such scenarios. Here we consider a minimal relaxation of…

Quantum Physics · Physics 2025-07-01 Ravi Kunjwal , Ognyan Oreshkov

Quantifying nonclassicality of a bosonic mode is an important but challenge task in quantum optics. Recently, the first nonclassicality measure based on the concept of operational resource theory has been proposed [Phys. Rev. Research 2,…

Quantum Physics · Physics 2020-10-14 Wenchao Ge , M. Suhail Zubairy

Quantum contextuality provides a fundamental signature of nonclassical behavior that cannot be explained by noncontextual hidden-variable models. We propose and experimentally implement a linear-optical setup for demonstrating…

Quantum Physics · Physics 2026-05-19 Jiaqi Liu , Bita Olamaei , Lijian Zhang , Ali Asadian , Saleh Rahimi-Keshari

Contextuality is a key feature of quantum mechanics, as was first brought to light by Bohr and later realised more technically by Kochen and Specker. Isham and Butterfield put contextuality at the heart of their topos-based formalism and…

Mathematical Physics · Physics 2023-05-09 Andreas Döring , Markus Frembs

Finding quantitative aspects of quantum phenomena which cannot be explained by any classical model has foundational importance for understanding the boundary between classical and quantum theory. It also has practical significance for…

Quantum Physics · Physics 2018-02-06 David Schmid , Robert W. Spekkens

Heisenberg's uncertainty principle, coherence and Bell nonlocality have been individually examined through many experiments. In this Letter, we systematically characterize all of this quantumness in a unified manner. We first construct…

The notion of contextuality, which emerges from a theorem established by Simon Kochen and Ernst Specker (1960-1967) and by John Bell (1964-1966), is certainly one of the most fundamental aspects of quantum weirdness. If it is a questioning…

Quantum Physics · Physics 2018-01-31 Hippolyte Dourdent

The set of maximally fermion-boson entangled Bell super-coherent states is introduced. A superposition of these states with separable bosonic coherent states, represented by points on the super-Bloch sphere, we call the Bell based…

Quantum Physics · Physics 2024-05-15 Oktay K Pashaev , Aygul Kocak