Collective Atomic Effects in Resonance Fluorescence.

This study has concerned itself with the effect of dispersion forces (dipole-dipole interaction) on the resonance fluorescence and on the absorption spectrum of a two-atom system undergoing cooperative evolution under the action of an external coherent driving field. It has been found that the dipole-dipole interaction is responsible for splitting the usual Rabi sideband of the fluorescence spectrum into a doublet, and for enhancing the height of the additional peaks located at twice the Rabi frequency from the resonance. The absorption spectrum is also modified when the atomic separation is sufficiently small. Moreover, it has been found that when the incident driving field suffers from phase fluctuations, the various features of the fluorescence spectrum are broadened, and, in particular, the Rabi doublet tends to merge into a single featureless structure.