  In this paper, an experiment of quantum diffraction of position-momentum
entangled photons from a straight sharp edge is presented. Path of a single
photon of an entangled pair is partially blocked by a sharp edge whereas the
other photon is detected at a stationary location without revealing the
which-path information of the other photon. Quantum diffraction pattern of the
sharp edge is revealed only in the correlated conditional detection of
spatially separated photons and no diffraction pattern is formed in local
detections of individual photons. Theoretical analysis of the quantum
diffraction of position-momentum entangled photons from a sharp edge is also
presented in this paper. Experimental measurements of the quantum diffraction
pattern are compared with theoretically calculated quantum diffraction pattern
of position-momentum entangled photons.
