Circular polarization correlation of the two photons emitted in the decay of metastable atomic deuterium

The circular polarization correlation of the two photons emitted simultaneously in the decay of metastable atomic deuterium has been measured for the first time. Taking full account of the imperfections of the achromatic quarter-wave plates and linear polarizers used in the experiments, it is concluded that the results are most probably consistent with the predictions of the quantum mechanical formalism but do not provide a test of Bell's inequality.