Persistence of Hardy's nonlocality in time

TL;DR

This paper demonstrates that Hardy's nonlocality argument's maximum success probability of 25% remains consistent across all finite-dimensional quantum systems, enabling tests of quantum properties in macroscopic systems.

Contribution

The study extends Hardy's nonlocality to all finite-dimensional systems, showing the maximum success probability is invariant at 25%, facilitating macroscopic quantum tests.

Findings

Maximum success probability of Hardy's argument is 25% for all finite-dimensional systems.

Hardy's nonlocality can be used to test quantum properties in macroscopic systems.

The invariance supports the universality of Hardy's nonlocality in quantum theory.

Abstract

Hardy's nonlocality argument, which establishes incompatibility of quantum theory with local-realism, can also be used to reveal the time-nonlocal feature of quantum states. For spin-1/2 systems, the maximum probability of success of this argument is known to be 25%. We show that this maximum remains 25% for all finite-dimensional quantum systems with suitably chosen observables. This enables a test of the quantum properties of macroscopic systems in analogy to the method of Leggett and Garg.