The Hardy's nonlocality argument

TL;DR

This paper reviews Hardy's nonlocality proof, an elegant and general approach demonstrating quantum nonlocality without Bell's inequality, highlighting its significance in understanding quantum theory's departure from local realism.

Contribution

It provides a comprehensive review of Hardy's nonlocality proof, emphasizing its simplicity and broad applicability as a key version of Bell's theorem without inequalities.

Findings

Hardy's proof offers a straightforward demonstration of quantum nonlocality.

It generalizes Bell's theorem without relying on inequalities.

The proof is considered the most elegant and accessible version of Bell's theorem.

Abstract

Certain predictions of quantum theory are not compatible with the notion of local-realism. This was the content of Bell's famous theorem of the year 1964. Bell proved this with the help of an inequality, famously known as Bell's inequality. The alternative proofs of Bell's theorem without using Bell's inequality are known as `nonlocality without inequality (NLWI)' proofs. We, review one such proof, namely the Hardy's proof which due to its simplicity and generality has been considered the best version of Bell's theorem.