Quantum Noise Reduction in Nondegenerate Four-wave Mixing above Threshold

Abstract

It is well known that nondegenerate four-wave mixing is one of the main mechanisms to produce nonclassical states of the electromagnetic field. As a matter of fact, the squeezing effect was first observed in this configuration1. Recently, sub-shot noise character in the fluctuations in the difference of the intensities of the two signal beams has been experimentally detected2, in analogy with the well known case of nondegenerate parametric oscillators3.