Directional Dicke Subradiance with Nonclassical and Classical Light Sources. (arXiv:1712.04312v1 [quant-ph])

We investigate Dicke subradiance of distant quantum sources in free space,
i.e., the spatial emission pattern of spontaneously radiating non-interacting
multi-level atoms or multi-photon sources, prepared in totally antisymmetric
states. We find that the radiated intensity is marked by a strong suppression
of spontaneous emission in particular directions. In resemblance to the
analogous, yet inverted, superradiant emission profiles of $N$ distant
two-level atoms prepared in symmetric Dicke states, we call the corresponding
emission pattern $\textit{directional Dicke subradiance}$. We also show that
higher order intensity correlations of the light incoherently emitted by
statistically independent thermal light sources display the same directional
Dicke subradiant behavior. We present measurements of directional Dicke
subradiance for $N = 2, \ldots, 5$ distant thermal light sources corroborating
the theoretical findings.