Until recently, a typical atom trap has consisted of a temperamental labyrinth of electric coils, custom-built and then fine-tuned and maintained by dedicated graduate students. Now scientists are adapting microchip technology to build robust miniaturized devices to trap and control tiny clouds of chilled atoms. Research groups in the U.S., Austria and Germany have demonstrated atom versions of optical fibers and beam splitters, as well as a magnetic "conveyor belt" for moving atoms around precisely--all on devices that look like crude computer chips. According to Jakob Reichel of the Max Planck Institute for Quantum Optics in Garching, Germany, "these microtraps are a promising tool to get quantum coherent interactions on the atomic scale." And that, he adds, "is the most important ingredient for a quantum computer."

For more than a decade, physicists have trapped and manipulated atoms (such as those in so-called Bose-Einstein condensation experiments) using macroscopic tools. Electric coils produce magnetic fields that trap a cloud of atoms and cool them below a thousandth of a kelvin, just a hair above absolute zero. In 1995 Kenneth G. Libbrecht and a student of his at the California Institute of Technology proposed that microscopic atom traps could be built on chips. Six years on, the proposal is being realized, using lithographically manufactured wires on chip surfaces to produce magnetic fields that can trap and guide atoms tens to hundreds of microns above the chip surface.

This article was originally published with the title Trapped over a Chip.

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