Controlling the degree of visibility of Young’s fringes with photon coincidence measurements

Abstract
Is it possible to detect the interference from an extended incoherent source with Young’s slits when the source-slits distance is such that all dimensions of the coherence area of the incident light beam are smaller than the distance between the slits? We have experimentally demonstrated that, under the above conditions, interference fringes can be obtained with a controlled degree of visibility by means of coincidence measurements between conujugated beams of the down-conversion luminescence.