Information causality in multipartite scenarios

TL;DR

This paper introduces a new multipartite formulation of the information causality principle, deriving inequalities that quantum resources satisfy and stronger-than-quantum correlations violate, with potential enhancements using multiple copies or noisy channels.

Contribution

It proposes a genuinely multipartite formulation of the information causality principle and derives necessary inequalities that distinguish quantum from stronger-than-quantum correlations.

Findings

Inequalities hold for all quantum resources.

Stronger-than-quantum correlations violate these inequalities.

Multiple copies and noisy channels can strengthen the approach.

Abstract

Bell nonlocality is one of the most intriguing and counter-intuitive phenomena displayed by quantum systems. Interestingly, such stronger-than-classical quantum correlations are somehow constrained, and one important question to the foundations of quantum theory is whether there is a physical, operational principle responsible for those constraints. One candidate is the information causality principle, which, in some particular cases, is proven to hold for quantum systems and to be violated by stronger-than-quantum correlations. In multipartite scenarios, though, it is known that the original formulation of the information causality principle fails to detect even extremal stronger-than-quantum correlations, thus suggesting that a genuinely multipartite formulation of the principle is necessary. In this work, we advance towards this goal, reporting a new formulation of the information causality principle in multipartite scenarios. By proposing a change of perspective, we obtain multipartite informational inequalities that work as necessary criteria for the principle to hold. We prove that such inequalities hold for all quantum resources, and forbid some stronger-than-quantum ones. Finally, we show that our approach can be strengthened if multiple copies of the resource are available, or, counter-intuitively, if noisy communication channels are employed.