Efficient interaction of light and matter

Throughout the history of quantum mechanics, the interaction of light and single atoms has been used for paradigmatic experiments. One way to enhance the efficiency of this interaction is to optimize the coupling of the light field to the atomic dipole in a free-space scenario, i.e. without imposing any boundary conditions. Among other requirements, focusing light onto the atom from almost the full solid angle is mandatory. This is implemented by using a parabolic mirror that is much deeper than its focal length. In the ongoing experiments, single atomic ions as well as nano crystals are used as quantum targets.

Illustration of a single photon pulse impinging onto an atom located in the focus of a deep parabolic mirror. The spatial intensity distribution of the incident light mode (depicted in green) creates the radiation pattern of a linear dipole after reflection off the parabolic surface. The amplitude of the light mode increases exponentially in time.