  We present the results of a study of the two-time correlation functions of a
dichotomously driven two-level system in contact with a thermal bath by using
corrections beyond the quantum regression theorem. In the strong
system-environment coupling regime, it is found that the noise parameters could
be tuned to control the magnitude of corrections at low environmental
temperatures. The motional averaging and narrowing effect of the external noise
was observed on the absorption and emission spectra of the two-state system.
Furthermore, effects similar to the destruction of tunneling and noise
enhancement of transport are observed in the dynamics of the two-time
correlations.
