Towards experiments to test violation of the original Bell inequality

TL;DR

This paper advocates for experimental tests of the original Bell inequality, emphasizing its foundational significance and potential for higher violations of classicality, supported by recent technological advances.

Contribution

It highlights the importance of testing the original Bell inequality over CHSH, considering recent technological progress and its stronger implications for quantum foundations.

Findings

Recent quantum technologies enable feasible tests of the original Bell inequality.

The original Bell inequality can show higher violations of classicality than CHSH.

Proposed experimental schemes include photon pairs and entangled electrons.

Abstract

The aim of this note is to attract attention of experimenters to the original Bell (OB) inequality which was shadowed by the common consideration of the CHSH inequality. There are two reasons to test the OB inequality and not the CHSH inequality. First of all, the OB inequality is a straightforward consequence to the EPR-argumentation. And only this inequality is related to the EPR-Bohr debate. However, the last statement can be objected by some experts working in quantum foundations. Therefore to convince experimenters to perform the OB-violation experiment, we prefer to concentrate on the second distinguishing feature of the OB inequality which was emphasized by I. Pitowsky. He pointed out that the OB inequality provides a higher degree of violations of classicality than the CHSH inequality. The main problem is that the OB inequality is derived under the assumption of perfect (anti-) correlations. However, the last years were characterized by the amazing development of quantum technologies. Nowadays, there exist sources producing with very high probability the pairs of photons in the singlet state. Moreover, the efficiency of photon detectors was improved tremendously. In any event one can start by proceeding with the fair sampling assumption. Another possibility is to use the scheme of Hensen et al. experiment for entangled electrons.