Cavity Quantum Electrodynamics with a Rydberg-blocked Atomic Ensemble

We report our experimental progress towards trapping of a cold ensemble with Rydberg-excited atoms in a high finesse optical cavity. Initial experiments are being performed in a moderate finesse (F$=$1200) cavity and high finesse (F$=$100,000) cavity experiment is currently under construction. This system will allow for realization of an optical non-linearity which is both non-dissipative and sufficiently strong to be useful at the single photon level. Such a system has numerous applications for quantum information, in particular, the implementation of a two-photon phase gate.