The cumulative resonance in atomic ground state induced by modulated light field

The interaction of an atomic system with a light beam, intensity-modulated at the ground-state Zeeman frequency is analysed by the dressed-atom method. When the light field is resonant, this interaction produces a new type of degereracy of dressed-atom energy levels which is not of level crossing type. This gives rise to the cumulative resonance with a width depending on the light intensity.