Abstract

Two-photon interferometry (polarization correlation included) provides an efficient tool for studying the foundations of quantum mechanics and the fundamental properties of the electromagnetic field. It has been pointed out that the study of two-photon interferometry may bring new hope to the development of quantum-measurement theory. Several two-photon-interfercncc experiments by using Mach–Zehnder interferometers have been reported.^1,2 In these experiments the light-quanta pairs generated from parametric downconversion are degenerate in frequency but nondegenerate in propagation direction. The photon pairs were directed to two input ports of a Mach-Zehnder interferometer, Higher than 50% second-order interference visibility (second order in intensity, fourth order in field) was observed when the pairs take equal optical paths to reach the input beam splitter of the interferometer from the down con version crystal. This phenomenon was considered to be a quantum effect.

© 1993 Optical Society of America