On the experimental violation of Mermin's inequality with imperfect measurements

TL;DR

This paper analyzes the potential for experimentally testing Mermin's inequality with larger spins using current photon detection technology, considering the impact of imperfect detection efficiencies.

Contribution

It demonstrates the feasibility of violating Mermin's inequality with spins larger than 1 despite nonideal detection efficiencies using a specific optical setup.

Findings

Violation of Mermin's inequality is achievable with spins > 1.

Current detection efficiencies are sufficient for experimental tests.

Optical losses impact the violation margin but do not prevent it.

Abstract

We investigate theoretically the feasibility of an experimental test of the Bell-type inequality derived by Mermin for correlated spins larger than 1/2. Using the Schwinger representation, we link the output fields of two two-mode squeezers in order to create correlated effective spins between two observers. Spin measurements will be performed by photon-number-resolved photodetection, which has recently come of age. We examine the effect of nonideal detection quantum efficiency---and any other optical loss---on the violation margin of Mermin's inequality. We find that experimental violation is well accessible for spins larger than 1 for quantum efficiencies compatible with the current state of the art.