Measurement of Time Delays in the Parametric Production of Photon Pairs

Abstract

The spread in time intervals between the two photons produced in the process of spontaneous parametric down-conversion in a potassium dihydrogen phosphate crystal has been measured with a time resolution of the order of 100 psec. The correlation time is found to be independent of the coherence time of the pump photons or of the propagation time through the crystal, consistent with recent theoretical predictions.