采用Pekar变分法研究了双参量非对称高斯势二能级体系中电子态的概率密度、跃迁频率及体纵光学声子自发辐射率,并讨论了其单参量抛物势近似。数值结果表明:选用双参量非对称高斯势描写量子点中电子的受限效应能够更恰当地反映电子态的波动性、电子运动的统计规律性及声子自发辐射率的量子化特性,而其单参量抛物势近似给出的结果较为简单和粗糙。材料的色散及电声耦合对二能级体系中电子态的概率分布、量子跃迁频率和体纵光学声子自发辐射率的影响不能忽略。

研究了一个囚禁于对称双势阱中的二能级原子与单模腔场的相互作用。 通过求解薛定谔方程,给出了整个系统波函数解析解和原子能级粒子数反转的解析表达式。 分析了当腔场初始态分别为粒子数态、相干态以及热态时原子粒子数反转随时间的演化情况, 并考虑了原子质心运动对粒子数反转的影响。结果表明通过选择合适的腔场初始态、势阱位 置及相关因素,可以有效地控制原子的自发辐射率。

The spontaneous emission rate of two interacting excited atoms near a dielectric interface is studied using the photon closed-orbit theory and the dipole image method. The total emission rate of one atom during the emission process is calculated as a function of the distance between the atom and the interface. The results suggest that the spontaneous emission rate depends not only on the atomic-interface distances, but also on the orientation of the two atomic dipoles and the initial distance between the two atoms. The oscillation in the spontaneous emission rate is caused by the interference between the outgoing electromagnetic wave emitted from one atom and other waves arriving at this atom after traveling along various classical orbits. Each peak in the Fourier transformed spontaneous emission rate corresponds with one action of photon classical orbit.

The formulas of the quantum electrodynamics have been applied to calculate the spontaneous emission rate of excited atom in dielectric microcavity. The results exhibit damping oscillating patterns which depend sensitively on the scaling parameter and geometrical structure. Compared with the case that the emitting atom is immersed in dielectric, the spontaneous emission rate is depressed obviously and the center or the mean value of the oscillations is intimately related to the real refractive index of the local position where the atom is. In order to explain this phenomenon, we utilize the closed-orbit theory to deal with the classical trajectories of the emitted photon, and extract the corresponding frequencies of the oscillations by Fourier transform. It is found that the oscillations can be represented in terms of the closed-orbits of the photon motion constrained in dielectric microcavity, thus providing another perspective on the spontaneous emission of atom sandwiched by dielectric slabs.