Figure 1

Schematic helical-phase-imprinted state preparation and far-field detection. (a) A single-photon source with orbital angular momentum (OAM) is absorbed by the atoms sitting on the stacked rings along \(\hat{z}\) (two ring arrays are shown here for illustration). The atomic system is then prepared into one of the super- or subradiant states, depending on OAM of light. In the process of spontaneous decay, the resonant dipole-dipole interaction M _μν couples μ^th and ν^th atoms on the stacked rings, and scatters the light collectively depending on the ring geometry of radius r, ϕ, and inter-ring distance d _z . (b) Typical light intensity (normalized) with OAM of Laguerre-Gaussian modes \({u}_{0}^{l}(r,\varphi )\) and associated helical phases e^ilϕ, for some beam waist radius w. (c) A far-field observer at \(\overrightarrow{R}\) sees the scattered light from a dipole \(\overrightarrow{p}\) at \({\overrightarrow{r}}_{\alpha }\) in 4π solid angle of mode \(\hat{k}\) characterized by θ′ and ϕ′.