Hardy's nonlocality argument as witness for post-quantum correlation

TL;DR

This paper demonstrates that Hardy's nonlocality argument can serve as a witness to identify post-quantum correlations in tripartite systems, highlighting the limitations of bipartite principles in distinguishing quantum from post-quantum correlations.

Contribution

It introduces a tripartite Hardy correlation example that is post-quantum yet satisfies bipartite information principles and GYNI inequality, extending the understanding of nonlocality.

Findings

Tripartite Hardy correlation can be post-quantum.

Such correlations can satisfy bipartite principles.

They can also satisfy the GYNI inequality.

Abstract

Recently, Gallego et.al. [Phys. Rev. Lett 107, 210403 (2011)] proved that any future information principle aiming at distinguishing between quantum and post-quantum correlation must be intrinsically multipartite in nature. We establish similar result by using device independent success probability of Hardy's nonlocality argument for tripartite quantum system. We construct an example of a tri-partite Hardy correlation which is post-quantum but satisfies not only all bipartite information principle but also the GYNI inequality.