Dipole Moment of a Superatom

Homodyne detection is used to measure the (collective) atomic dipole moment for an atomic ensemble that is prepared in a superposition of spatially phased Dicke states having at most two excitations (a so-called "superatom"). Homodyne detection allows one to isolate the contributions to the radiated intensity that depend linearly on the average value of the collective atomic dipole moment operator. Depending on whether the atom-reference field interference is constructive or destructive, either super-Poisson or sub-Poisson statistics for the combined field is observed.