Atomic Merry-Go-Round

By Fenella Saunders|Monday, April 1, 2002
At a time when colleagues are building larger, ever-faster circular atom smashers, Michael Chapman's work looks like a parody. He and his fellow physicists at Georgia Tech have built a particle-storage ring less than an inch wide; the cold atoms inside travel at just two miles per hour. But this toylike device has a serious goal: It may allow scientists to control atoms the way lasers control light.

Photograph courtesy of Georgia Institute of Technology

Chapman's team calls their ring the Nevatron, a play on the mile-wide Tevatron particle accelerator at Fermilab outside Chicago. The Nevatron consists of two closely spaced circular wires attached to an aluminum plate. Electric current creates a magnetic field that confines atoms between the wires. The researchers cool rubidium atoms until they barely move and inject them in. "Then they just loop around like a carnival ride," Chapman says.

He envisions using the Nevatron as a sensitive gyroscope for aircraft guidance systems. Two streams of cold atoms running in opposite directions around the ring would interfere with each other, a process that is highly sensitive to motion. A properly tuned device could therefore pick up every change in the flight path of an airplane. Ultimately, Chapman hopes to cool the atoms further so they emerge from the Nevatron as a Bose-Einstein condensate, a state of matter in which atoms blend together into a quantum blur. Under those conditions, atoms form a coherent beam, like the photons of light in a laser. An atom laser could serve as a super-accurate clock or as a tool for exploring the enigmas of the quantum world, where atoms can cancel each other out or exist in two places at the same time.

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