Comment on "Reliability of Bell-inequality measurements using polarization correlations in parametric-down-conversion photon sources"

Abstract

In a recent article [Phys. Rev. A 50, R2803 (1994)] De Caro and Garuccio state that many parametric-down-conversion sources cannot be used in tests of Bell's inequalities because they produce quantum-mechanical product states. Here we point out that not only have suitable sources already been proposed in the literature, but experiments not suffering from the problems cited by the authors have also been reported.