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Quantum contextuality is the key concept which explains the fact that the result of a measurement is not independent of the context in which it is found. It is observed to be an intrinsic feature, i.e., neither entanglement nor spatial…

Quantum Physics · Physics 2023-02-23 Firat Diker , Zafer Gedik

In the Contextuality-by-Default theory random variables representing measurement outcomes are labeled contextually, i.e., not only by what they measure but also under what conditions (in what contexts) the measurements are made, including…

Quantum Physics · Physics 2018-12-11 Ehtibar N. Dzhafarov

We employ a trapped ion to study quantum contextual correlations in a single qutrit using the 5-observable KCBS inequality, which is arguably the most fundamental non-contextuality inequality for testing Quantum Mechanics (QM). We quantify…

Quantum Physics · Physics 2018-11-21 M. Malinowski , C. Zhang , F. M. Leupold , A. Cabello , J. Alonso , J. P. Home

We combine the study of resources in measurement-based quantum computation (MBQC) with that of quantum solutions to linear constraint systems (LCS). Contextuality of the input state in MBQC has been identified as a key resource for quantum…

Quantum Physics · Physics 2026-01-19 Markus Frembs , Cihan Okay , Ho Yiu Chung

In classical physics, properties of the objects exist independently on the context, i.e. whether and how measurements are performed. Quantum physics showed this assumption to be wrong and that Nature is indeed "contextual". Contextuality…

Quantum measurement is a physical process. What physical resources and constraints does quantum mechanics require for measurement to produce the classical world we observe? Treating measurement as a fully unitary quantum process, our goal…

Quantum Physics · Physics 2025-12-09 Vishal Johnson , Ashmeet Singh , Reimar Leike , Philipp Frank , Torsten Enßlin

We show that the phenomenon of quantum contextuality can be used to certify lower bounds on the dimension accessed by the measurement devices. To prove this, we derive bounds for different dimensions and scenarios of the simplest…

Quantum Physics · Physics 2014-06-12 Otfried Gühne , Costantino Budroni , Adan Cabello , Matthias Kleinmann , Jan-Åke Larsson

Contextuality is a distinctive feature of quantum theory and a fundamental resource for quantum computation. However, existing examples of contextuality in high-dimensional systems lack the necessary robustness required in experiments. Here…

Contextuality is a feature of quantum correlations. It is crucial from a foundational perspective as a nonclassical phenomenon, and from an applied perspective as a resource for quantum advantage. It is commonly defined in terms of hidden…

We demonstrate in this paper that the probabilities for sequential measurements have features very different from those of single-time measurements. First, they cannot be modelled by a classical stochastic process. Second, they are…

Quantum Physics · Physics 2009-11-11 Charis Anastopoulos

Studying the extent to which realism is compatible with quantum mechanics teaches us something about the quantum mechanical universe, regardless of the validity of such realistic assumptions. It has also recently been appreciated that these…

Quantum Physics · Physics 2007-09-28 Nicholas Harrigan , Terry Rudolph

The presence of contextuality in quantum theory was first highlighted by Bell, Kochen and Specker, who discovered that for quantum systems of three or more dimensions, measurements cannot be viewed as revealing pre-existing properties of…

Quantum Physics · Physics 2017-04-07 Andrew W. Simmons , Joel J. Wallman , Hakop Pashayan , Stephen D. Bartlett , Terry Rudolph

A central result in the foundations of quantum mechanics is the Kochen-Specker theorem. In short, it states that quantum mechanics is in conflict with classical models in which the result of a measurement does not depend on which other…

A generalisation of quantum contextuality to the case of many indentical particles is presented. The model consists of a finite collection of modes that can be occupied by N particles, either bosons or fermions. Measurement scenarios allow…

Quantum Physics · Physics 2017-02-01 Pawel Kurzynski

We present a protocol to evaluate the expectation value of the correlations of measurement outcomes for ensembles of quantum systems, and use it to experimentally demonstrate--under an assumption of fair sampling--the violation of an…

Quantum Physics · Physics 2010-06-11 O. Moussa , C. A. Ryan , D. G. Cory , R. Laflamme

Identifying when observed statistics cannot be explained by any reasonable classical model is a central problem in quantum foundations. A principled and universally applicable approach to defining and identifying nonclassicality is given by…

Contextuality is considered as an intrinsic signature of non-classicality, and a crucial resource for achieving unique advantages of quantum information processing. However, recently there have been debates on whether classical fields may…

Quantum Physics · Physics 2019-02-28 Aonan Zhang , Huichao Xu , Jie Xie , Han Zhang , Brian J. Smith , M. S. Kim , Lijian Zhang

We introduce contextual values as a generalization of the eigenvalues of an observable that takes into account both the system observable and a general measurement procedure. This technique leads to a natural definition of a general…

Quantum Physics · Physics 2010-06-16 J. Dressel , S. Agarwal , A. N. Jordan

Recent experiments have shown that nature violates noncontextual inequalities regardless of the state of the physical system. So far, all these inequalities involve measurements of dichotomic observables. We show that state-independent…

Quantum Physics · Physics 2011-04-20 Angel R. Plastino , Adan Cabello

Quantum contextuality describes situations where the statistics observed in different measurement contexts cannot be explained by a measurement independent reality of the system. The most simple case is observed in a three-dimensional…

Quantum Physics · Physics 2024-08-28 Holger F. Hofmann