  We discuss the creation of non-classical light from collective atomic states
that are prepared in a ring-shaped lattice. These states are realized by
exploiting the strong interaction between atoms in high lying energy levels -
so-called Rydberg states - and yield a resource for creating excitations of the
electromagnetic field that carry few photons. We characterize the properties of
these photonic states showing that they are determined by the interplay between
the ring geometry, the structure of the atomic resource states and the
collectivity in the photon emission which is controlled by the lattice spacing.
The system permits the creation of single photons with well-defined orbital
angular momentum and two-photon states that are entangled in orbital angular
momentum.

Quantum Physics;Atomic Physics