Fourth-Order Interference in Femtosecond Spontaneous Parametric Down-Conversion
-
Abstract
We report a fourth-order interference experiment in which pairs of photons are produced in spontaneous parametric down-conversion pumped by femtosecond pulses interfere in a Hong-Ou-Mandel interferometer. The visibility of the interference is (64±4)%, exceeding the bound of 50% predicted by classical interference theory. -