Applicability of the rotating wave approximation to a multilevel atomic system driven by a polychromatic field

we study the distortions in the dispersion and absorption spectra that arise when rotating wave approximation (RWA) is applied to multilevel atomic system driven by a polychromatic field. The density matrix equations are solved numerically without applying the RWA and when using it. The obtained polarization spectra are compared with each other in terms of maximum and frequency-averaged deviations.