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It was presented by Cabello and Nakamura [A. Cabello, Phys. Rev. Lett. 90, 190401 (2003)], that the Kochen-Specker theorem applies to two dimensions if one uses Positive Operator-Valued Measures. We show that contextuality in their models…

Quantum Physics · Physics 2008-07-24 Andrzej Grudka , Pawel Kurzynski

Contextuality and nonlocality are two fundamental properties of nature. Hardy's proof is considered the simplest proof of nonlocality and can also be seen as a particular violation of the simplest Bell inequality. A fundamental question is:…

Quantum Physics · Physics 2013-11-01 Adan Cabello , Piotr Badziag , Marcelo Terra Cunha , Mohamed Bourennane

If noncontextuality is defined as the robustness of a system's response to a measurement against other simultaneous measurements, then the Kochen-Specker arguments do not provide an algebraic proof for quantum contextuality. Namely, for the…

Quantum Physics · Physics 2020-04-30 Gábor Hofer-Szabó

The Wigner function of a finite-dimensional system can be constructed via dual pairing of a density matrix with the Stratonovich-Weyl kernel. Following Kenfack and $\dot{\text{Z}}$yczkowski, we consider the indicator of nonclassicality of a…

Quantum Physics · Physics 2021-12-30 Vahagn Abgaryan , Arsen Khvedelidze , Astghik Torosyan

Weak value measurements have recently given rise to a large interest for both the possibility of measurement amplification and the chance of further quantum mechanics foundations investigation. In particular, a question emerged about weak…

Wigner negativity and genuine multipartite entanglement (GME) are key nonclassical resources that enable computational advantages and broader quantum-information tasks. In this work, we prove two theorems for multimode continuous-variable…

Quantum Physics · Physics 2025-10-31 Lin Htoo Zaw , Jiajie Guo , Qiongyi He , Matteo Fadel , Shuheng Liu

The negativity of the Wigner function is discussed as a measure of the non classicality and the quantum interference pattern obtained therein as a possible measure of the entanglement between the two modes of the vortex states. This measure…

Quantum Physics · Physics 2014-06-05 Anindya Banerji , Ravindra P. Singh , Abir Bandyopadhyay

We propose a Wigner function based parameter that can be used as an indicator of quantum chaos. This parameter is defined as "entropy" from the time-dependence of "non-classicallity" proposed in \cite{KZ04}. We perform our considerations…

Quantum Physics · Physics 2012-04-02 A. Kowalewska-Kudłaszyk , J. K. Kalaga , W. Leoński

Viewed as approximations to quantum mechanics, classical evolutions can violate the positive-semidefiniteness of the density matrix. The nature of this violation suggests a classification of dynamical systems based on classical-quantum…

Quantum Physics · Physics 2009-11-06 Salman Habib , Kurt Jacobs , Hideo Mabuchi , Robert Ryne , Kosuke Shizume , Bala Sundaram

The nonclassicality of photon-added coherent fields in the thermal channel is investigated by exploring the volume of the negative part of the Wigner function which reduces with the dissipative time. The Wigner functions become positive…

Quantum Physics · Physics 2015-06-26 Shang-Bin Li , Justin Liu , Xu-Bo Zou , Guang-Can Guo

There has been a growing interest, both in physics and psychology, in understanding contextuality in experimentally observed quantities. Different approaches have been proposed to deal with contextual systems, and a promising one is…

Data Analysis, Statistics and Probability · Physics 2015-11-10 J. Acacio de Barros , Janne Kujala , Gary Oas

Wigner's Friend scenarios push the boundaries of quantum theory by modeling agents, along with their memories storing measurement outcomes, as physical quantum systems. Extending these ideas beyond quantum theory, we ask: in which physical…

Quantum Physics · Physics 2025-10-08 Nuriya Nurgalieva , V. Vilasini

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

We study the possibility of giving a classical interpretation to quantum projective measurements for a particle described by a pure Gaussian state whose Wigner function is non-negative. We analyze the case of a projective measurement which…

Quantum Physics · Physics 2009-11-13 Amir Kalev , Ady Mann , Pier A. Mello , Michael Revzen

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

The Quantum Ergodic Conjecture equates the Wigner function for a typical eigenstate of a classically chaotic Hamiltonian with a delta-function on the energy shell. This ensures the evaluation of classical ergodic expectations of simple…

Quantum Physics · Physics 2015-05-20 E. Zambrano , W. P. Karel Zapfe , Alfredo M. Ozorio de Almeida

In a recent work [S. Asthana. New Journal of Physics 24.5 (2022): 053026], we have shown the interrelation of different nonclassical correlations in multiqubit systems with quantum coherence in a single logical qubit. In this work, we…

Quantum Physics · Physics 2023-03-21 Sooryansh Asthana , V. Ravishankar

As a phenomenon encompassing measurement incompatibility and Bell nonlocality, quantum contextuality is not only central to our understanding of quantum mechanics, but also an essential resource in many quantum information processing tasks.…

Quantum Physics · Physics 2024-03-19 Xiao-Dong Yu , Isadora Veeren , Otfried Gühne

When it isn't possible to tell two distinct experimental procedures apart purely from their input/output statistics, then it seems a plausible hypothesis that the two procedures must be physically identical. We call such a hypothesis…

Quantum Physics · Physics 2021-02-17 Ravi Kunjwal

The existence of incompatible measurements is often believed to be a feature of quantum theory which signals its inconsistency with any classical worldview. To prove the failure of classicality in the sense of Kochen-Specker…

Quantum Physics · Physics 2024-04-05 John H. Selby , David Schmid , Elie Wolfe , Ana Belén Sainz , Ravi Kunjwal , Robert W. Spekkens
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