sentences:  Since this correlation function includes the steady state limits of the density matrix, where formula_49 and formula_50, and the spectrum is nonzero, it is clear to see that the Mollow triplet remains the spectrum for the fluoresced light even in a steady state solution.The study of correlation functions is critical to the study of quantum optics as the Fourier transform of the correlation function is the energy spectral density.Thus the two-time correlation function is a useful tool in the calculation of the energy spectrum for a given system.