Cavity quantum electrodynamics with neutral atoms

We utilize a strongly-coupled atom cavity system to demonstrate optical nonlinearities on the single atom level. We employed higher-order resonances of the strongly-coupled system to realize a two-photon gateway where resonant photons are absorbed and emitted in pairs and extended the work to higher-order correlations. In the same system we demonstrated the ability of a single atom to produce quadrature-squeezed light, which has fluctuations of amplitude or phase that are below the shot-noise level.

_{Selected references:
A. Ourjoumtsev, et al., „Observation of squeezed light from one atom excited with two photons“. Nature 474, 623 (2011)}

_{M. Koch, et al., „Three-Photon Correlations in a Strongly Driven Atom-Cavity System“. Physical Review Letters 107, 023601 (2011)}

_{A. Kubanek, et al., „Two-Photon Gateway in One-Atom Cavity Quantum Electrodynamics“. Physical Review Letters 101, 203602 (2008)}

_{I. Schuster, et al., „Nonlinear spectroscopy of photons bound to one atom“. Nature Physics 4, 382–385 (2008)}