Generalised contextuality of continuous variable quantum theory can be revealed with a single projective measurement

Fuente: arXiv
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Auteurs principaux: Jokinen, Pauli, Weilenmann, Mirjam, Plávala, Martin, Pellonpää, Juha-Pekka, Kiukas, Jukka, Uola, Roope
Format: Preprint
Publié: 2026
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author Jokinen, Pauli
Weilenmann, Mirjam
Plávala, Martin
Pellonpää, Juha-Pekka
Kiukas, Jukka
Uola, Roope
author_facet Jokinen, Pauli
Weilenmann, Mirjam
Plávala, Martin
Pellonpää, Juha-Pekka
Kiukas, Jukka
Uola, Roope
contents Generalized contextuality is a possible indicator of non-classical behaviour in quantum information theory. In finite-dimensional systems, this is justified by the fact that noncontextual theories can be embedded into some simplex, i.e. into a classical theory. We show that a direct application of the standard definition of generalized contextuality to continuous variable systems does not envelope the statistics of some basic measurements, such as the position observable. In other words, we construct families of fully classical, i.e. commuting, measurements that nevertheless can be used to show contextuality of quantum theory. To overcome the apparent disagreement between the two notions of classicality, that is commutativity and noncontextuality, we propose a modified definition of generalised contextuality for continuous-variable systems. The modified definition is based on a physically-motivated approximation procedure, that uses only finite sets of measurement effects. We prove that in the limiting case this definition corresponds exactly to an extension of noncontextual models that benefits from non-constructive response functions. In the process, we discuss the extension of a known connection between contextuality and no-broadcasting to the continuous-variable scenario, and prove structural results regarding fixed points of infinite-dimensional entanglement breaking channels.
format Preprint
id arxiv_https___arxiv_org_abs_2601_14067
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Generalised contextuality of continuous variable quantum theory can be revealed with a single projective measurement
Jokinen, Pauli
Weilenmann, Mirjam
Plávala, Martin
Pellonpää, Juha-Pekka
Kiukas, Jukka
Uola, Roope
Quantum Physics
Mathematical Physics
Generalized contextuality is a possible indicator of non-classical behaviour in quantum information theory. In finite-dimensional systems, this is justified by the fact that noncontextual theories can be embedded into some simplex, i.e. into a classical theory. We show that a direct application of the standard definition of generalized contextuality to continuous variable systems does not envelope the statistics of some basic measurements, such as the position observable. In other words, we construct families of fully classical, i.e. commuting, measurements that nevertheless can be used to show contextuality of quantum theory. To overcome the apparent disagreement between the two notions of classicality, that is commutativity and noncontextuality, we propose a modified definition of generalised contextuality for continuous-variable systems. The modified definition is based on a physically-motivated approximation procedure, that uses only finite sets of measurement effects. We prove that in the limiting case this definition corresponds exactly to an extension of noncontextual models that benefits from non-constructive response functions. In the process, we discuss the extension of a known connection between contextuality and no-broadcasting to the continuous-variable scenario, and prove structural results regarding fixed points of infinite-dimensional entanglement breaking channels.
title Generalised contextuality of continuous variable quantum theory can be revealed with a single projective measurement
topic Quantum Physics
Mathematical Physics
url https://arxiv.org/abs/2601.14067