级联型四能级系统由于具有6个可能的光学跃迁通道, 因而有许多现实的子类型可供光学量子相干效应的理论和实验探讨。利用布尔代数方法, 按照可能存在的跃迁通道, 结合电偶极跃迁选择定则, 研究了级联四能级系统的所有的通道子类型, 得到了17个三通道和2个四通道的现实通道子类型。然后, 仅仅按照涉及的光场的强弱来区分, 又得到了168种现实强度子类型。这种子类型的结构多样性为量子光学、量子信息科学和精密光谱学等理论及应用研究提供了更灵活的能级选择。

The cascade four-level system has six possible optical transition channels and provides many real subtypes for theoretical and experimental studies about quantum coherence effects. Using Boolean algebra method, according to possible existing transition channels, combining electric dipole selection rule, all channel subtypes of cascade four-level scheme are studied, the realistic channel subtypes of 17 three transition channels and 2 four transition channels are got. Furthermore, 168 real intensity subtypes appear when one distinguishes each of related laser field intensities only. This multiformality of realistic channel and intensity subtypes provides more subtle energy level scheme-choosing chances for quantum optics, quantum information science, precise laser spectroscopy, etc.