Stimulated emission studies of ultracold Rydberg atoms

Rydberg atoms have many novel properties that make them appealing, most noticeably their long lifetimes and very strong dipole interactions. This dissertation describes experiments involving the optical detection and manipulation of ultracold Rydberg atoms using a novel stimulated emission probe.;This stimulated emission probe was first used to explore the dynamics of ultracold Rydberg atoms. Two-photon excitation creates Rydberg atoms which can be observed via loss of atoms from the MOT, or by fluorescent emission. The addition of a stimulated-emission probe enabled further measurement of the rate of transfer from the Rydberg state. A model was developed to better understand the data, revealing that superradiant transfer is an important mechanism in the atom dynamics at these densities.;We have further performed non-degenerate four-wave mixing through the Rydberg states using the stimulated emission probe, causing preferential emission into a diffraction limited direction. This result can be optimized by detuning the excitation lasers from the Rydberg resonance, resulting in up to 50 percent of the light emitted in a diffraction limited direction.;The final experiment described in this dissertation is the investigation of atom-atom interactions within a small excitation volume. We have shown that these interactions can be enhanced through the application of resonant microwaves. Suppression of Rydberg atom excitation was qualitatively observed and quantitatively analyzed using a universal scaling law. This gave a measure of the atom-atom interaction strength in agreement with the theoretical prediction. This represents a large advance in the understanding of Rydberg atom interactions, and their possible use in quantum computing or single photon applications.