ATOMIC-CASCADE EXPERIMENT WITH DETECTION OF THE RECOIL ATOM

Bell's inequalities cannot be violated in atomic-cascade experiments, even with ideal apparatus, due to the three-body character of the atom ic decay. Here we propose a new experiment that would block this looph ole by means of a suitable selection of an ensemble of photon pairs. A threshold value for the quantum efficiency is found which may allow t he discrimination between quantum mechanics and local-hidden-variables theories. Experimental requirements for performing such a test are di scussed.