Single-Atom Addressing in Microtraps for Quantum-State Engineering using   Rydberg Atoms
  We report on the selective addressing of an individual atom in a pair of single-atom microtraps separated by $3\;\mu$m. Using a tunable light-shift, we render the selected atom off-resonant with a global Rydberg excitation laser which is resonant with the other atom, making it possible to selectively block this atom from being excited to the Rydberg state. Furthermore we demonstrate the controlled manipulation of a two-atom entangled state by using the addressing beam to induce a phase shift onto one component of the wave function of the system, transferring it to a dark state for the Rydberg excitation light. Our results are an important step towards implementing quantum information processing and quantum simulation with large arrays of Rydberg atoms. 
Henning Labuhn, Sylvain Ravets, Daniel Barredo, Lucas B\'eguin,   Florence Nogrette, Thierry Lahaye, and Antoine Browaeys
quant-ph physics.atom-ph