Bell’s Theorem: The Forgotten Loophole and How to Exploit It

John F. Clauser

Justo Pastor Lambare

ARTUR K. EKERT

Wayne C. Myrvold

The hidden-variables model constructed by Karl Hess and Walter Philipp is claimed by its authors to exploit a “loophole” in Bell's theorem; according to Hess and Philipp, the parameters employed in their model extend beyond those considered by Bell. Furthermore, they claim that their model satisfies Einstein locality and is free of any “suspicion of spooky action at a distance.” Both of these claims are false; the Hess-Philipp model achieves agreement with the quantum-mechanical predictions, not by circumventing Bell's theorem, but via Parameter Dependence.

Gisin, Nicolas, Gisin, B V

A local hidden variable model exploiting the detection loophole to reproduce exactly the quantum correlation of the singlet state is presented. The model is shown to be compatible with both the CHSH and the CH Bell inequalities. Moreover, it bears the same rotational symmetry as spins. The reason why the model can reproduce the quantum correlation without violating the Bell theorem is that in the model the efficiency of the detectors depends on the local hidden variable. On average the detector efficiency is limited to 75%.

Louis Vervoort