Apparently, the possibility of being off 1 second every 70 million years was just too much for the National Institute of Standards and Technology.Ã‚Â So NIST recently announced a new ultra-precise clock based on the oscillations of a mercury ion.Ã‚Â The new clock, tested and measured over the past 5+ years, should have an accuracy such that drift will be less than 1 second over 400 million years.Ã‚Â It will still take some time before this clock becomes the new standard, but the extra precision certainly suggests it will happen.
A prototype mercury optical clock was originally demonstrated at NIST in 2000. Over the last five years its absolute frequency has been measured repeatedly with respect to NIST-F1. The improved version of the mercury clock is the most accurate to date of any atomic clock, including a variety of experimental optical clocks using different atoms and designs.
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“We finally have addressed the issue of systemic perturbations in the mercury clock. They can be controlled, and we know their uncertainties,” says NIST physicist Jim Bergquist, the principal investigator. “By measuring its frequency with respect to the primary standard, NIST-F1, we have been able to realize the most accurate absolute measurement of an optical frequency to date. And in the latest measurement, we have also established that the accuracy of the mercury-ion system is at a level superior to that of the best cesium clocks.”
And if you just want to learn more about atomic clocks and how they work, check out the NIST atomic clock page.
[tags]Atomic clock, Ultra-precision[/tags]