Original URL: http://www.theregister.co.uk/2014/04/05/nist_new_atomic_clock/

Time is on their side: NIST's new atomic clock accurate for 300 MEEELLION years

Boffins rock around the clock

By Iain Thomson

Posted in Science, 5th April 2014 00:42 GMT

Vid Some people are nuts about knowing the correct time, but the boffins at the US National Institute of Standards and Technology (NIST) have taken such habits further than anyone else with a new atomic clock that's accurate to 10 trillionths of a second per day.

The clock, snappily dubbed NIST-F2, uses the frequency of a particular transition in the cesium atom – which is 9,192,631,770 vibrations per second – to measure the passing of time with such accuracy that the boffins calculate it would take over 300 million years for the clock to slip one second behind.

"Most people don't realize it, but we all rely on the exquisite precision of atomic clocks for much of the technology we use every day. The modern telecommunications and computer network systems that we're using right now require synchronization to about 1 millionth of a second per day," said Tom O'Brian, chief of NIST's time and frequency division.

"The electric power grid that is distributed across the continent that's powering our webinar equipment right now also requires synchronization to about 1 millionth of a second per day. And the GPS system that's used to navigate airlines and our personal cars requires synchronization to about 1 billionth of a second per day."

The new clock uses six infra-red lasers to bunch cesium atoms into a ball within a vacuum chamber and cool them to as close to absolute zero temperatures as possible. A pair of vertical lasers pushes this ball of atoms 1.3 meters up a column, which is nitrogen-cooled to reduce the effects of thermal radiation.

During its passage, the cesium ball is bathed with microwaves, which alters the state of some of the atoms. The atoms are then excited with a laser and their frequency is checked against the frequency rate of cesium to measure time as exactly as possible.

"NIST-F2 is a great advance on this continuing amazing march of science and technology. But as great as it is, scientists at NIST and across the world are already working on the next generation of atomic clocks that will be even better," O'Brian said.

The NIST-F2's predecessor, the F1, has been America's official timepiece since 1999, but the new clock will now replace it after testing at the International Bureau of Weights and Measures in France.

But as any engineer knows, relying on a single data point is a dumb idea, which is why NIST is contributing plans and parts to build a second version of the clock, dubbed IT-CsF2, at the Istituto Nazionale di Ricerca Metrologica in Italy. It will also carry on running the F1 clock to see how future clocks can be made even more accurate. ®