CALCULATION OF MICROWAVE MULTIPHOTON TRANSITION-PROBABILITY

In a phenomenological two-level model, by using Floquet method, we dir ectly calculate the multiphoton transition probability between the Ryd berg states of an alkali-metal atom in strong microwave fields. The co nvergence of the truncated Floquet matrix, and the influences of param eters upon the multiphoton resonant spectra are discussed. The results show that our method can give clearer physical picture and better res ults about the multiphoton transition than indirect methods. Moreover, our method can easily be generalized to treat multi-level models.