Emergence of correlations in strongly interacting ultracold Rydberg gases

This thesis experimentally explores the application of strongly interacting states of Rydberg atoms as means to introduce and control correlations in many-body systems. A new apparatus has been built, which combines high atomic densities possible using optical dipole traps with the ability to detect and probe Rydberg atoms via both field ionization detection and electromagnetically induced transparency. In the first study, the interaction induced excitation of Rydberg atom pairs ('antiblockade') is demonstrated using detuned laser excitation. This provides the possibility to engineer spatial correlations and to control interactions between Rydberg atoms. We then investigate the effects of Rydberg-Rydberg interactions and correlations on the spontaneous evolution of the system to an ultracold plasma. The initial correlations between Rydberg atoms should be preserved, suggesting a new route to overcome disorder-induced heating and to enter new strongly coupled regimes. Finally the back-action of Rydberg-Rydberg interactions on propagating light fields is explored. Dissipative interactions between dark-state polaritons give rise to a strongly nonlinear optical response and sub-Poissonian statistics of polaritons which reflect the emergence of correlations in both the atomic and light fields. Combined, these experiments help elucidate the effects of Rydberg induced correlations on diverse physical systems involving atoms, ions and photons