二能级原子与高品质因子腔的自发辐射特性

Characteristics of spontaneous emission from a two-level atom in a very high Q cavity

用全量子理论研究二能级原子单模腔耦合系统,通过理论推导和数值计算得出系统的自发辐射光谱和平均粒子数密度.共振时腔与原子的发射光谱在强耦合与弱耦合区域有所不同,腔发射光谱分裂只出现于强耦合区域,而原子发射光谱由于腔感应透明效应在弱耦合区域出现了缺口.本文系统地研究了原子与腔在失谐时的发射光谱,在好腔机理(腔线宽小于原子线宽g)原子与腔即使在大失谐时腔发射出腔频率的光子,这给当前实验上困惑的特性提供了一个理论依据.为了给腔感应透明效应一个新的深入了解,还研究了原子与腔平均粒子数密度随时间的演化,以及平均粒子数密度与光强度之间的关系.

In this paper we investigate a coupled system of an initially excited two-level atom coupled to a monomode cavity,and compute spontaneous emission spectrum and mean population density emitted by the atom and the cavity using the quantum theory that accounts for theoretical derviation and numerical calculation.The spectra emitted separately by the atom and the cavity in of strong coupling region are dramatically different from those in weak coupling region at resonance.The cavity spectrum line splitting in the strong coupling region,however,a hole exists in the atomic spectrum in the weak coupling region.We study systematically the emission spectra when the atom and the cavity are detuned,and the results show that if the cavity linewidth is much smaller than the atomic linewidth（good cavity regime）,photons are emitted at the cavity frequency even if the atom and the cavity are strongly detuned,and provide theoretic foundation for the apparently puzzling feature observed in the recent experiment.In this paper we computate the atomic and the cavity mean population densities each as a function of time and their relation to the luminous intensity,and offer a new insight into civity induced transparency effect.