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

Abstract

Loading only single atoms into an optical trap with an efficiency in excess of 80% has now been achieved by manipulating the collisions between pairs of atoms. Such a process has previously been limited to about 50% efficiency. The technique will aid the development of neutral-atom-based quantum logic gates. 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.