Violation of a new Wigner inequality with high angular momenta

TL;DR

This paper extends the Wigner inequality to broader measurement schemes and demonstrates its violation using high angular momentum entangled photons, challenging local realism under lossy conditions.

Contribution

It introduces a generalized Wigner inequality applicable to single-outcome measurements and applies it to high angular momentum photon pairs, showing a novel violation of local realism.

Findings

Violation of local realism with high angular momentum photons

The inequality is effective under lossy measurement conditions

Demonstrates the largest quantum quanta violation to date

Abstract

In the study of systems that cannot be described classically, the Wigner inequality, has received only a small amount of attention. In this paper we extend the Wigner inequality - originally derived in 1969 - and show how it may be used to contradict local realism with only coincidence detections in the absence of two-outcome measurements - that is, for any system where only one possible result of a pair of potential outcomes can be registered. It thus encapsulates a much broader class of measurement schemes than could previously violate a local-realistic inequality. This is possible due to an assumption of "extended fairness" on the measurement outcomes, which we posit is highly plausible. We then apply this inequality to a recently constructed setup with access to entangled pairs of photons with very high angular momenta, in which no previously derived local-realistic inequality could successfully be used without making very broad assumptions. To our knowledge this experiment constitutes a violation of local realism with the largest quanta to date. We thus demonstrate the versatility of this inequality under very lossy conditions.