Polarization-entangled photon generation using partial spatially coherent pump beam.

The generation of two photon fields, to date, has been demonstrated utilizing a fully coherent pump beam. In this paper we demonstrate, the theoretical and experimental generation of polarization entangled single photon pairs by varying the spatial coherence of the pump beam. The effect of the pump beam spatial coherence on the visibility of a polarization-entangled single photon source is investigated. A comparison of the visibility measurements using a fully coherent and partially coherent pump beam is performed. It is shown that the partial coherence of the pump beam contributes to an increase in the visibility. The coherence properties of the beam are significant for free-space optical transmission in particular for long range free-space quantum communication.