Generalized Hardy's Paradox

TL;DR

This paper introduces a comprehensive framework for n-particle Hardy's paradoxes, demonstrating stronger conflicts with local realism and proposing experimental tests, thereby advancing the understanding of quantum nonlocality.

Contribution

It generalizes Hardy's paradox to n particles, showing stronger violations and deriving new Hardy's inequalities for detecting Bell nonlocality.

Findings

Existence of generalized Hardy's paradoxes for any n ≥ 3 with success probability up to 1/2^{n-1}

Stronger paradoxes than previous versions in demonstrating quantum nonlocality

Construction of the most general Hardy's inequalities for Bell nonlocality detection

Abstract

Here we present the most general framework for $n$-particle Hardy's paradoxes, which include Hardy's original one and Cereceda's extension as special cases. Remarkably, for any $n\ge 3$ we demonstrate that there always exist generalized paradoxes (with the success probability as high as $1/2^{n-1}$) that are stronger than the previous ones in showing the conflict of quantum mechanics with local realism. An experimental proposal to observe the stronger paradox is also presented for the case of three qubits. Furthermore, from these paradoxes we can construct the most general Hardy's inequalities, which enable us to detect Bell's nonlocality for more quantum states.