Rydberg Mediated Interactions Atom-by-Atom and Photon-by-Photon

Recent years have seen a remarkable development in our ability to manipulate individual atoms and individual photons, including the ability to design strong and controlled interactions. The interaction range between highly excited atomic states (Rydberg states) can substantially exceed an optical wavelength, which allows one to trap and manipulate individual atoms optically, yet induce controlled interactions on demand to implement quantum gates, create highly entangled states, or study quantum phase transitions.
Alternatively, the Rydberg interaction can be used to create effective strong interactions between individual photons traveling in an atomic medium. I will discuss recent results on large maximally entangled GHZ states with up to 20 atoms, novel implementations of quantum gates in arrays of individually trapped atoms, and the experimental realization of strong repulsive interactions between individual photons.