Atom interferometer precise as laser gyroscopes

17 Jun 2002

Atom waves can be used to detect rotational effects, such as the revolution of the Earth, with as much sensitivity as most commercial laser gyroscopes, new experiments have demonstrated.

David Pritchard (dave@amo.mit.edu) and his coworkers at MIT pass a beam of sodium atoms through an atom interferometer, a device which splits individual atoms into wavelets and recombines them to form interference patterns of light and dark fringes. Rotating the interferometer itself while the atom waves travel freely through the device makes the fringes shift from their usual positions.

The MIT device can detect rotation rates as slow as one-hundredth of a degree per minute, comparable to the sensitivity of good-quality commercial laser gyroscopes used to detect rotational effects in autos and tanks, but only about one-tenth the sensitivity of laser gyroscopes used in inertial guidance systems in aircraft. With further improvements, atom interferometers may one day easily surpass the sensitivity of laser interferometers because atom wavelengths can be tens of thousands of times smaller. In addition, the atoms' much slower speeds compared to light means the interferometer has more time to rotate while the particles travel through the device and thereby can create more appreciable fringe shifts, researchers say.