Experimental Test of Generalized Hardy's Paradox

TL;DR

This paper experimentally confirms multipartite generalized Hardy's paradoxes, demonstrating a stronger quantum nonlocality conflict than previous multipartite Hardy's paradoxes without using inequalities.

Contribution

It provides the first experimental test of the multipartite generalized Hardy's paradoxes, strengthening the demonstration of quantum nonlocality beyond previous multipartite versions.

Findings

Confirmed multipartite Hardy's paradoxes experimentally

Demonstrated stronger quantum nonlocality conflict

Extended the framework to include previous Hardy's paradoxes

Abstract

Since the pillars of quantum theory were established, it was already noted that quantum physics may allow certain correlations defying any local realistic picture of nature, as first recognized by Einstein, Podolsky and Rosen. These quantum correlations, now termed quantum nonlocality and tested by violation of Bell's inequality that consists of statistical correlations fulfilling local realism, have found loophole-free experimental confirmation. A more striking way to demonstrate the conflict exists, and can be extended to the multipartite scenario. Here we report experimental confirmation of such a striking way, the multipartite generalized Hardy's paradoxes, in which no inequality is used and the conflict is stronger than that within just two parties. The paradoxes we are considering here belong to a general framework [S.-H. Jiang \emph{et al.}, Phys. Rev. Lett. 120, 050403 (2018)], including previously known multipartite extensions of Hardy's original paradox as special cases. The conflict shown here is stronger than in previous multipartite Hardy's paradox. Thus, the demonstration of Hardy-typed quantum nonlocality becomes sharper than ever.