Mirror-assisted backscattering interferometry to measure the first-order correlation function of the light emitted by quantum scatterers

We present a method to obtain the first-order temporal correlation function, g((1))(tau), of the light scattered by an assembly of pointlike quantum scatterers, or equivalently its spectral power distribution. This method is based on the mirror-assisted backscattering interferometric setup. The contrast of its angular fringes was already linked to the convolution of g((1))(tau) for different Rabi frequencies taking into account the incoming spatial intensity profile of the probe beam, but we show here that by simply adding a half wave plate to the interferometer in a specific configuration, the fringe contrast becomes g((1))(tau) of the light scattered by atoms, which are now all subjected to the same laser intensity. This method has direct application to obtaining the saturated spectrum of quantum systems. We discuss some nontrivial aspects of this interferometric setup and propose an analogy with a double Mach-Zehnder interferometer. (AU)