Near-deterministic preparation of a single atom in an optical microtrap

*T. Grünzweig,*A. Hilliard,*M. McGovern*& M. F. Andersen

Neutral atoms stored in optical traps are strong candidates for a physical realization of a quantum logic device1, 2. Far off-resonance optical traps provide conservative potentials and excellent isolation from the environment, and they may be arranged to produce arbitrary arrays of traps, where each trap is occupied by a single atom that can be individually addressed3, 4, 5, 6. At present, significant effort is being expended on developing two-qubit gates based on coupling individual Rydberg atoms in adjacent optical microtraps7, 8, 9. A major challenge associated with this approach is the reliable generation of single-atom occupancy in each trap, as the loading efficiency in the past experiments has been limited to 50% (refs 4, 7, 8, 10, 11, 12). Here we report a loading efficiency of 82.7% in an optical microtrap. We achieve this by manipulating the collisions between pairs of trapped atoms through tailored optical fields and directly observing the resulting single atoms in the trap.

**Groupmeeting by Graham Edge, Jan 26th, 2011**