Quantum electrodynamics of a driven three-level atom near the edge of a photonic band gap

In the first part of this thesis, the coherent control of spontaneous emission for a three level atom located within a photonic band gap (PBG) material is demonstrated. Spontaneous emission from the three level atom can be totally suppressed or strongly enhanced depending on the relative phase between the steady-state control laser coupling the two upper levels and the pump laser pulse used to create an excited state of the atom in the form of a coherent superposition of the two upper levels. Unlike the free space case, the steady-state inversion of the atomic system is strongly dependent on the externally prescribed initial conditions. This non-zero steady state population is robust to decoherence effects provided that the Rabi frequency of the control laser field exceeds the rate of dephasing interactions. As a result, such a system may be relevant for a single-atom, phase sensitive, optical memory device on the atomic scale. Provided that coherence can be maintained between the two upper atomic levels, the model system can also act as a qubit to encode information for quantum computation.; In the second part of this thesis, the resonance Raman scattering of light from a three-level atom in the Λ configuration embedded in a photonic band gap material is studied as a direct experimental probe for the photon-atom bound state discussed in the first part. The one particle spectrum of the system is demonstrated to consist of either a continuous part with energy lying outside the gap or a single discrete mode with energy lying inside the gap. The discrete mode, which occurs when both of the allowed atomic transitions lie inside the gap, can be treated as a photon-atom bound state in which the radiation is localized in the vicinity of the atom. In the case of the continuous spectrum, the Rayleigh and Stokes lines are shifted as well as narrowed (or broadened) as the corresponding transition frequencies are shifted relative to the upper band edge, providing a distinctive experimental signature of atom-photon interactions near a photonic band edge.