Abstract

We have discovered theoretically and confirmed experimentally that a vast improvement over the traditional (type-I) downconversion sources (in which both correlated photons have the same polarization) is possible by using type-II downconversion (in which the correlated photons are orthogonally polarized).¹ In previous systems it was necessary to use a number of very carefully aligned extra optical elements, beam splitters, mirrors, etc., to obtain and measure the quantum-mechanical entangled states required for many fundamental experiments.^2,3

© 1995 Optical Society of America