arXiv:1602.06117v1
arXiv:1602.06117v1
By mapping the strong interaction between Rydberg excitations in ultra-cold atomic ensembles onto single photons via electromagnetically induced transparency it is now possible to realize a nonlinear optical medium which can modify light on the level of individual photons. We review the theoretical concepts and the experimental state-of-the-art of this exciting new field, and discuss first applications in the field of all-optical quantum information processing.