Tests of Bell inequality with arbitrarily low photodetection efficiency and homodyne measurements

TL;DR

This paper demonstrates that combining homodyne and photodetection measurements can violate Bell inequalities even with very low photodetection efficiency, advancing the feasibility of loophole-free Bell tests.

Contribution

It introduces hybrid measurement schemes that enable Bell inequality violations at arbitrarily low detection efficiencies, expanding potential experimental approaches.

Findings

Violations achieved with low photodetection efficiency

Hybrid measurements outperform traditional methods

Applicable to atom-photon and photon-photon systems

Abstract

We show that hybrid local measurements combining homodyne measurements and photodetection provide violations of a Bell inequality with arbitrarily low photodetection efficiency. This is shown in two different scenarios: when one part receives an atom entangled to the field mode to be measured by the other part and when both parts make similar photonic measurements. Our findings promote the hybrid measurement scenario as a candidate for loophole-free Bell tests beyond previous expectations.