Quantum computers have moved a step closer with a beam-steering system that can focus bursts of laser light onto single atoms. The system can be compared to the projectors used in laser light shows, but it is far faster and smaller, and accurate to atom scale.

For quantum computing, laser light must be aimed and focused so accurately that light meant for one atom will not instead affect its neighbors. In the new system, micromirrors point to each target atom in as little as 5 µs, about 1000 times faster than sophisticated beam-steering mirrors developed for optical communications switching, not to mention units used for light shows. The laser pulses also manipulated the quantum properties of each target atom in a line of five rubidium-87 atoms as intended – and without disturbing any of the neighboring atoms, which were just 8.7 µm apart.

Researchers from Duke University and the University of Wisconsin-Madison collaborated on the system, which was described in Applied Physics Letters, Vol. 97, p. 134101 (2010). Duke researchers designed the micromirror system, and the atomic physics experiments were performed at the University of Wisconsin-Madison.