Bounding quantum contextuality with lack of third-order intereference

TL;DR

This paper demonstrates that the absence of third-order interference in quantum experiments implies the principle of Consistent Exclusivity, helping unify quantum nonlocality and contextuality explanations and bounding Bell inequality violations.

Contribution

It shows that lack of third-order interference implies the E principle, linking interference properties to foundational quantum principles.

Findings

Lack of third-order interference implies the E principle.

This implication bounds CHSH-Bell inequality violations to 2.883.

Provides a unified understanding of quantum nonlocality and contextuality.

Abstract

Recently many simple principles have been proposed that can explain quantum limitations on possible sets of experimental probabilities in nonlocality and contextuality experiments. However, few implications between these principles are known. Here it is shown that lack of irreducible third-order interference (a generalisation of the idea that no probabilistic interference remains unaccounted for once we have taken into account interference between pairs of slits in a $n$-sit experiment) implies the principle known as the E principle or Consistent Exclusivity (that, if each pair of a set of experimental outcomes are exclusive alternatives in some measurement, then their probabilities are consistent with the existence of a further measurement in which they are all exclusive). This is a step towards a more unified understanding of quantum nonlocality and contextuality, which promises to allow derivations of important results from minimal, easily grasped assumptions. As one example, this result implies that lack of third order interference bounds violation of the CHSH-Bell inequality to 2.883.