ua nt - p h / 07 02 19 4 v 2 6 M ar 2 00 7 Multiatom cooperative emission following single - photon absorption : Dicke - state dynamics

We investigate conditions under which multiatom absorption of a single photon leads to cooperative decay. Our analysis reveals the symmetry properties of the multiatom Dicke states underlying the cooperative decay dynamics and their spatio-temporal manifestations, particularly, the forward-directed spontaneous emission investigated by Scully et al. Dicke pioneered the notion of cooperative spontaneous emission by a collection of N atoms, highlighted by the " superradiant " N 2-scaling of the emission rate into resonant modes [1]. His work has prompted numerous studies of the dependence of cooperative spontaneous emission upon the initial preparation (cooperative dipole moment and excitation), as well as the spatial symmetry and density (interatomic distances) of the multiatom sample [2, 3, 4, 5, 6, 7]. These factors determine the degree of cooperativity, which may be attributed to multiatom interference of radiated photons. This cooperativity may range from maximal enhancement (superradiance or su-perfluorescence), first observed in [3], to maximal suppression (subradiance) [4, 5, 7], corresponding to constructive or destructive interference, respectively. Similar effects in neutron scattering on crystalline lattices have also