Quantum and Super-quantum enhancements to two-sender, two-receiver channels

TL;DR

This paper explores how super-quantum correlations, modeled by PR-boxes, can enhance communication capacities in two-sender, two-receiver channels beyond quantum entanglement limits, revealing new non-locality insights.

Contribution

It demonstrates that PR-boxes can enable perfect communication in certain channels and shows a capacity separation where super-quantum resources outperform quantum entanglement.

Findings

PR-boxes enable perfect communication where classical and quantum strategies fail.

Super-quantum resources can surpass quantum entanglement in channel capacity.

A tunable parameter shows a capacity hierarchy: super-quantum > quantum > classical.

Abstract

We study the consequences of 'super-quantum non-local correlations' as represented by the PR-box model of Popescu and Rohrlich, and show PR-boxes can enhance the capacity of noisy interference channels between two senders and two receivers. PR-box correlations violate Bell/CHSH inequalities and are thus stronger -- more non-local -- than quantum mechanics; yet weak enough to respect special relativity in prohibiting faster-than-light communication. Understanding their power will yield insight into the non-locality of quantum mechanics. We exhibit two proof-of-concept channels: first, we show a channel between two sender-receiver pairs where the senders are not allowed to communicate, for which a shared super-quantum bit (a PR-box) allows perfect communication. This feat is not achievable with the best classical (senders share no resources) or quantum entanglement-assisted (senders share entanglement) strategies. Second, we demonstrate a class of channels for which a tunable parameter achieves a double separation of capacities; for some range of \epsilon, the super-quantum assisted strategy does better than the entanglement-assisted strategy, which in turn does better than the classical one.