Bell-type polarization experiment with pairs of uncorrelated optical photons.

• We have performed a Bell-type experiment using two separate and independent sources of optical photons. • We have observed violation of the Clauser-Horne inequality. • The distinction between the concepts of state-preparation and measurement may help to understand our results. • We comment that in such experiments the analyzing instrument and the final state-preparation instrument should not coincide. We present a Bell-type polarization experiment using two independent sources of polarized optical photons, and detecting the temporal coincidence of pairs of uncorrelated photons which have never been entangled in the apparatus. Very simply, our measurements have tested the quantum-mechanical equivalent of the classical Malus' law on an incoherent beam of polarized photons obtained from two separate and independent laser sources greatly reduced in intensities. The outcome of the experiment gives evidence of violation of the Bell-like inequalities. Drawing the conclusions of the present work, we invoke the distinction between the concepts of state-preparation and measurement to understand this result. [ABSTRACT FROM AUTHOR]