Observation of nonclassical effects in the interference of two photons

Abstract

By measuring the joint probability for the detection of two photons at two points as a function of the separation between the points, we have demonstrated the existence of nonclassical effects in the interference of signal and idler photons in parametric down-conversion. In principle, the detection of one photon at one point rules out certain positions where the other photon can appear. © 1987 The American Physical Society.