The multiparticle Bell inequalities revealed by the polarization measurements on the output fields generated by parametric down conversion were discussed. The inequalities were revealed in the regime of both low-and high-output intensity and by spatially separated systems comprising of more than one particle. The findings provided an opportunity to test the predictions of quantum mechanics for spatially separated higher spin states. The results were applicable to both vacuum-state signal and idler inputs and to the quantum-injected parametric amplifiers.
Physical Review A - Atomic, Molecular, and Optical Physics, Vol. 66, no. 3 (Sep 2002), pp. 338011-3380110