Abstract

An Einstein-Podolsky-Rosen (EPR) experiment by means of second-order interference of a two-photon entangled state was studied for the first time with a 50-ps coincidence time window. Franson proposed a new type of EPR experiment¹ for measurement of position and time correlation in contrast to the historical measurement of polarization correlation^2-4 and to study Bell's inequality. This effect arises from the existence of two-photon entangled states.⁵ A spontaneous parametric downconversion process creates a two-photon state that is highly correlated in frequency and time regardless of the distance between the photon pair after they leave the nonlinear crystal.

© 1992 Optical Society of America