Dicke-like superradiance of distant noninteracting atoms

Fully excited two-level atoms separated by less than the transition wavelength cooperatively emit light in a short burst, a phenomenon called superradiance by R. Dicke in 1954 [Phys. Rev. 93, 99 (1954)]. The burst is characterized by a maximum intensity scaling with the square of the number of atoms N and a temporal width reduced by N compared to the single atom spontaneous decay time. Both effects are usually attributed to a synchronization of the electric dipole moments of the atoms occurring during the process of light emission. Contrary to this explanation, it was recently shown by use of a quantum path description that the peak intensity results from the quantum correlations among the atoms when occupying symmetric Dicke states. Here we investigate from this perspective the temporal evolution of the ensemble, starting in the small sample limit, i.e., when the atoms have mutual separations much smaller than the transition wavelength lambda and pass down the ladder of symmetric Dicke states. In addition, we explore the temporal evolution for the case of distant noninteracting atoms with mutual separations much larger than lambda. We show that in this case a similar superradiant burst of the emitted radiation is observed if the quantum correlations of the atoms are generated by conditional photon measurements retaining the atomic ensemble within or close to the symmetric subspace.

Automated summary

It has been discovered that fully excited two-level atoms can cooperatively emit light in a phenomenon called superradiance. The intensity of the superradiant burst is proportional to the square of the number of atoms, and the temporal width is reduced. Recent studies have shown that the peak intensity is due to the quantum correlations among the atoms when occupying symmetric Dicke states. The temporal evolution of the ensemble is investigated in two scenarios: when the atoms are closely spaced and when they are far apart. It is found that a similar superradiant burst occurs if the quantum correlations are generated by conditional photon measurements retaining the atomic ensemble within or close to the symmetric subspace.