Effects of twin-beam "squashed" light on a three-level atom - art. no. 043805

An electro-optical feedback loop can make in-loop light (squashed light) wh ich produces a photocurrent with noise below the standard quantum limit (su ch as squeezed light). We investigate the effect of squashed light interact ing with a three-level atom in the cascade configuration and compare it to the effects produced by squeezed light and classical noise. It turns out th at one master equation can be formulated for all three types of light and t hat this unified formalism can also be applied to the evolution of a two-le vel atom. We show that squashed light does not mimic all aspects of squeeze d light, and in particular, it does not produce the characteristic linear i ntensity dependence of the population of the upper-most level of the cascad e three-level atom. Nevertheless, it has nonclassical transient effects in the de-excitation.