A next-generation atomic clock that tops previous records for accuracy in clocks based on neutral atoms has been demonstrated by physicists at JILA, a joint institute of the National Institute of Standards and Technology (NIST) and the University of Colorado at Boulder. The new clock, based on thousands of strontium atoms trapped in grids of laser light, surpasses the accuracy of the current U.S. time standard based on a "fountain" of cesium atoms. The work was reported last week in Science Express.
JILA's experimental strontium clock is now the world's most accurate atomic clock based on neutral atoms, more than twice as accurate as the NIST-F1 standard cesium clock located just down the road at the NIST campus in Boulder. The JILA strontium clock would neither gain nor lose a second in more than 200 million years, compared to NIST F-1's current accuracy of over 80 million years.
The strontium clock uses light, which has higher frequencies than the microwaves used in NIST-F1. Because the frequencies are higher, the clock divides time into smaller units, offering record precision. 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 and be chosen as the next international standard.
For more details and video see "Collaboration Helps Make JILA Strontium Atomic Clock 'Best in Class'." [link removed because it is no longer active.]