  In this paper we propose some Hamiltonian characterizing the interaction of
the two-level atom and both the single radiation mode and external field, which
might be a generalization of that of Sch{\"o}n and Cirac (quant-ph/0212068). We
solve them in the strong coupling regime under some conditions (the rotating
wave approximation, resonance condition and etc), and obtain unitary
transformations of four types to perform Quantum Computation.
