The world’s smallest atomic clock
DOI: 10.1063/1.2408602
The world’s smallest atomic clock has been built at NIST in Boulder, Colorado. About the size of a rice grain (see photo), the clock is built around a semiconductor laser, micro-optics, a heater, and a microcell filled with cesium atoms. Using only 73 mW of electrical power, the clock has a precision of 2.5 × 10−10 over 1 second and 2.5 × 10−11 over 250 seconds. Far more precise clocks are available—some are good to about one part in 1015—but they can require a large tabletop’s worth of equipment. This new, tiny, low-power, high-precision clock is also likely to be cheap; it uses standard microfabrication techniques whereby the same process sequence can make thousands of the physics packages on silicon wafers. The timekeeper could be used, for example, in a variety of hand-held, battery-operated devices. (
