Testing Hardy nonlocality proof with genuine energy-time entanglement

TL;DR

This paper reports two experimental tests of Hardy nonlocality using energy-time entangled photons, demonstrating nonlocal correlations without the post-selection loophole, advancing quantum nonlocality verification methods.

Contribution

The study presents the first experimental realization of Hardy nonlocality tests with energy-time entanglement, avoiding the post-selection loophole common in previous experiments.

Findings

Successful implementation of Hardy ladder test with energy-time entangled photons

Experiments are free of the post-selection loophole

One test is equivalent to a Bell test with minimal detection efficiency

Abstract

We show two experimental realizations of Hardy ladder test of quantum nonlocality using energy-time correlated photons, following the scheme proposed by A. Cabello \emph{et al.} [Phys. Rev. Lett. \textbf{102}, 040401 (2009)]. Unlike, previous energy-time Bell experiments, these tests require precise tailored nonmaximally entangled states. One of them is equivalent to the two-setting two-outcome Bell test requiring a minimum detection efficiency. The reported experiments are still affected by the locality and detection loopholes, but are free of the post-selection loophole of previous energy-time and time-bin Bell tests.