Macroscopic noncontextuality as a principle for almost-quantum correlations

Joseph Henson, Ana Belen Sainz

Research output: Contribution to journalArticle (Academic Journal)peer-review

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Quantum mechanics allows only certain sets of experimental results (or “probabilistic models”) for Bell-type quantum nonlocality experiments. A derivation of this set from simple physical or information theoretic principles would represent an important step forward in our understanding of quantum mechanics, and this problem has been intensely investigated in recent years. “Macroscopic locality,” which requires the recovery of locality in the limit of large numbers of trials, is one of several principles discussed in the literature that place a bound on the set of quantum probabilistic models. A similar question can also be asked about probabilistic models for the more general class of quantum contextuality experiments. Here, we extend the macroscopic locality principle to this more general setting, using the hypergraph approach of Acín, Fritz, Leverrier, and Sainz [Comm. Math. Phys. 334(2), 533–628 (2015)], which provides a framework to study both phenomena of nonlocality and contextuality in a unified manner. We find that the set of probabilistic models allowed by our macroscopic noncontextuality principle is equivalent to an important and previously studied set in this formalism, which is slightly larger than the quantum set. In the particular case of Bell scenarios, this set is equivalent to the set of “almost-quantum” models, which is of particular interest since the latter was recently shown to satisfy all but one of the principles that have been proposed to bound quantum probabilistic models, without being implied by any of them (or even their conjunction). Our condition is the first characterization of the almost-quantum set from a simple physical principle.
Original languageEnglish
Article number042114
Number of pages11
JournalPhysical Review A: Atomic, Molecular and Optical Physics
Issue number4
Publication statusPublished - 13 Apr 2015

Bibliographical note

Date of Acceptance: 24/03/2015


  • quantum correlations
  • foundations of quantum theory
  • post-quantum correlations


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