Higher-tech atomic clock

The National Institute of Standards and Technology has created a new, highly accurate clock that exploits technology first developed in its investigation of futuristic quantum computers.

The new atomic clock relies on natural vibrations in a single aluminum atom. The current most accurate clock keys its timekeeping to vibrations of a single mercury atom. Both clocks are at least 10 times more accurate than the current U.S. time standard.

The new aluminum atom clock uses logic technology developed in NIST's quantum computing program. Quantum computers solve problems using quantum mechanics, which directs the smallest particles of matter and light.

Many researchers think quantum computing research could generate designs for extremely fast and powerful computers that would not be constrained by the limits on shrinking the features, or individual components, etched on current-generation integrated circuits.

Highly accurate clocks are used to synchronize global telecommunications networks. They also facilitate deep-space communications, as well as ground-based satellite control and positioning, NIST said.

Next-generation clocks may also lead to new types of gravity sensors. The improved sensors could enable geologists to find new oil and gas reservoirs, as well as other underground resources. Scientists potentially could use the advanced timekeeping systems to facilitate fundamental Earth science studies, NIST said.

'The aluminum clock is very accurate because it is insensitive to background magnetic and electric fields, and also to temperature,' says Till Rosenband, the NIST physicist who built the clock. 'It has the lowest known sensitivity of any atomic clock to temperature, which is one of the most difficult uncertainties to calibrate.'

Both clocks are based on natural vibrations in electrically charged atoms known as ions. NIST said the advanced clocks would neither gain nor lose a second in over 1 billion years, if they could run for such a long time.

By comparison, the U.S. time standard clock, based on neutral cesium atoms, can run without gaining or losing a second for about 80 million years.

Today the mercury clock is about 20 percent more accurate than the aluminum clock but the designers say both experimental clocks could be improved further.

Laboratories around the world are developing optical clocks based on a variety of different designs and atoms; it is not yet clear which design will emerge as the best candidate for the next international standard.

NIST scientists compared the accuracy of the mercury and aluminum clocks for a year. They calculated relative frequencies of the two clocks, which determines their accuracy, to 17 decimal places.

About the Author

Kathleen Hickey is a freelance writer for GCN.

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