An Apparatus for Studying Rydberg Polaritons in an Optical Resonator

In electromagnetically induced transparency (EIT) involving a Rydberg state, the dark state polaritons, or Rydberg polaritons, consist of a superposition of an atomic Rydberg excitation and a photon. Rydberg polaritons offer a route towards realizing long-range interactions in a quantum-degenerate atomic and optical system. The Rydberg component gives rise to strong, long-range van der Waals interactions between polaritons, while the photonic component determines the kinetic energy of the polaritons. We report on progress towards the realization of a two-dimensional quantum gas of Rydberg polaritons in a high finesse optical cavity. The strong atom-light coupling in the cavity suppresses decoherence arising from atomic motion, polariton collisions, and the photonic kinetic energy. A sufficient polariton lifetime gives access to coherent quantum many-body physics, including the phase transition between a superfluid and crystalline ground state and few-body blockade effects.