The Quantum Coherence Effect Of Atomic System Embedded In Photonic Band Gap Structures

We investigate the quantum coherence phenomena of atomic system embedded in photonic band gap (PBG) structures. Our research focuses on the dark line in the spontaneous emission spectrum and the transparency to a weak probe light in this system. We pay much attention to the understanding of these coherence phenomena. In studying the spontaneous emission dark line, besides calculating the effect of various density of mode (DOM), we also find that the initial population of atomic states can make the dark line move. In studying the transparency to the weak probe light, we calculate the steady and transient properties of the linear susceptibility of the atomic system with a non-singular DOM. We analyze the characteristic of the reduced group velocity near the PBG transparency window and the defect mode transparency window.Furthermore, we investigate the properties of population transfer in these transparency phenomena. We prove that, in the PBG transparency window, there is no coherent population trapping in the final state. In other words, the atomic system is a quasi-steady state at this time. However,in the defect mode transparency window, in the final state, the atomic system reach coherent population trapping, it is in "dark state". Based on this, it is possible to use the steady population of the atomic system to memorize the intensity and phase information of a probe laser field.