17-05-2025
NIST set its new atomic clock in motion, and it's astoundingly precise
A new atomic clock is one of the world's best timekeepers, researchers say — and after years of development, the 'fountain'-style clock is now in use helping keep official U.S. time.
Known as NIST-F4, the clock is at the Boulder, Colorado, campus of the National Institute of Standards and Technology (NIST).
The clock relies on cesium atoms, which oscillate between quantum states at a frequency of over 9 billion times per second. NIST-F4 uses lasers to cool a ball of cesium atoms to near absolute zero, then measures the frequency of the atoms as they pass through a microwave chamber.
As they rise and fall like water in a fountain, the atoms oscillate, 'ticking' more than 9 billion times per second.
The length of that second is so reliable that the clock would be off by less than a second if it had started running 100 million years ago, researchers say.
In an article in Metrologia evaluating the clock's accuracy, researchers say the clock is accurate enough to help calibrate coordinated universal time (UTC).
It took months to assess the super-precise clock, its inventors say. All that testing was worth it: The agency 'has already benefited significantly from the fountain's high uptime and the reliability of its performance,' Liz Donley, chief of NIST's time and frequency division, said in a news release.
Once certified by the International Bureau of Weights and Measures (BIPM), NIST-F4 will become one of a small cadre of clocks used to calibrate coordinated universal time. It's already in use as part of the agency's UTC(NIST) timescale, which provides official time for the United States.
