Trapped atoms in cavity QED for quantum optics and quantum information.

摘要

One of the requirements for the physical implementation of many protocols in quantum information science is the ability to convert quantum information from stationary to travelling form and transmit it over long distances. The strong coupling domain of cavity quantum electrodynamics (QED) provides a near-ideal setting for the pursuit of these goals. In addition, cavity QED is a unique system for the study of open quantum systems and quantum coherence. Cavity QED experiments have entered a new era in recent years, with the advent of single atom intracavity trapping.; Experiments described in this thesis represent significant progress in these areas. Beginning with a tremendous set of improvements to far-off-resonance optical trapping of single Cs atoms in a Fabry-Perot resonator, we have undertaken a series of investigations in which strongly coupled trapped atoms have been used for quantum optics and quantum information. These improvements in trapping go beyond quantitative lengthening of storage times, in that the trap is largely insensitive to the atom's internal state.; As a result of this unique property of the optical trap, a breakthrough was made in the continuous observation time of trapped atoms. Individual atoms can be observed for times of order 1 second, and this scheme enables real-time monitoring and measurement of the number of atoms strongly coupled to the cavity. This enables deterministic preparation of a particular atom number of the experimenter's choice.; Using single trapped atoms in our cavity, we have also experimentally realized the one-atom laser in a regime of strong coupling. The unconventional characteristics of this system are explored in detail, including strongly nonclassical output. This represents a significant milestone of longstanding interest in the quantum optics community, and goes beyond previous work with atomic beams where there was a fluctuating atom number in the cavity.; Finally, we have achieved the first deterministic generation of single photons in a setting suitable for quantum networks. By illuminating a strongly coupled, trapped atom by classical laser pulses, single photons have been generated on demand, with intrinsic efficiency near unity. Although a great deal of work remains to configure this system as a true node in a quantum network, the ground-work has been laid for progress in the near future, where one goal is to create an entangled state of two atoms in distantly separated cavities.