Chinese Physics
Constructive interference via collision-aided radiative excitation
Xihua Yang, Zhenrong Sun, Ding Liang-En, Zugeng Wang
Abstract
We have studied theoretically constructive interference via collision-aided radiative excitation in an open four-level system using a density matrix approach. The four-level system consists of a Λ-type three-level quantum-beat configuration driven by one laser field and a fourth level coupled by a vacuum mode. It is shown that through the incoherent process (collision), coherence between widely-separated doublets and subsequent constructive interference can be realized. We analyse the effects of the collision-induced coherent and incoherent decay rates, laser intensity and energy separation of the doublets on the interference. Meanwhile, the constructive interference between the two transition pathways 3P 1/2 -4D and 3P 3/2 -4D via equal-frequency hybrid excitation and collision-aided radiative excitation in an Na 2 -Na system is experimentally observed. A good agreement between the theoretical and experimental results is obtained.