Cavity QED in Microsphere and Fabry-Perot Cavities

Citation

Buck, Joseph Robert (2003) Cavity QED in Microsphere and Fabry-Perot Cavities. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/585P-6F46. https://resolver.caltech.edu/CaltechETD:etd-05292003-214249

Abstract

A long-standing ambition in the field of cavity quantum electrodynamics has been to trap single atoms inside high-Q cavities in a regime of strong coupling. Our goal has been to develop techniques for trapping that are compatible with strong coupling and that do not interfere with the cavity QED interactions. This is crucial for applications to quantum computation and communication. We have accomplished this goal by creating a trapping potential through an intracavity FORT at the 'magic' wavelength for Cesium, 935.6 nm. Unlike typical FORTs, where the signs of the AC-Stark shifts for excited and ground states are opposite, our trap causes small shifts to the relevant transition frequencies, enabling a trapping potential for the center-of-mass motion that is largely independent of the internal atomic state. This has enabled us to achieve extended trapping times (3 sec) for individual Cesium atoms in cavity QED in a regime of strong coupling. Although our longest lifetimes are obtained when the probing fields are turned off, the atoms can also be continuously monitored, leading to mean trapping times of 0.4 sec, with some atoms observed for over 1 sec.

An important tool for studying atom-field interactions is a high-Q cavity with small mode volume. Considerable effort has been made in advancing our capabilities for high-Q resonators. While much of our work involves Fabry-Perot cavities, some of the highest quality optical resonators to date have been achieved with the whispering gallery modes (WGMs) of quartz microspheres (Q = 8 x 10⁹). Therefore, considerable effort has been given to understanding the usefulness of microspheres for cavity QED with strong coupling. We have also worked at manufacturing high-Q microspheres suitable for cavity QED. To this end, we have been successful at making spheres with a radius of 10 microns and Q = 10⁷.

Thesis Files