  Taking nonlinear effect into account, we study theoretically the transmission
properties of photons in a one-dimensional coupled cavities, the cavity located
at the center of the cavity array is coupled to a two-level system. By the
traditional scattering theory, we calculate the transmission rate of photons
along the cavities, and discuss the effect of nonlinearity on the photon
transport. The results show that the controllable two-level system can act as a
quantum switch in the coherent transport of photons. The dynamics of such a
system is also studied by numerical simulations, the effect of the atom-field
detuning and nonlinearity on the dynamics is shown and discussed.
