Resonance fluorescence from two identical atoms in a standing-wave field

We investigate the resonance fluorescence spectrum from two identical atoms driven by a strong standing-wave field. We find interesting modifications of the Mollow spectrum, caused by interferences between the two atoms, and in particular a succession of ''dark'' and ''bright'' states as one of the atoms is moved to successive nodes of the field. Large enough separation between the atoms leads to their decorrelation and the disappearance of these interferences, the atoms acting then as independent radiators. From a technical viewpoint, we also illustrate how the use of superoperators in Liouville space keeps the discussion transparent and provides a convenient tool for numerical calculations.