Heralding a new age of terrific timekeeping, a research group led by a National Institute of Standards and Technology (NIST) physicist has unveiled an experimental strontium atomic clock that has set new world records for both precision and stability—key metrics for the performance of a clock.
The clock is in a laboratory at JILA, a joint institute of NIST and the University of Colorado Boulder.
Described in a new paper in Nature,* the JILA strontium lattice clock is about 50 percent more precise than the record holder of the past few years, NIST’s quantum logic clock.** Precision refers to how closely the clock approaches the true resonant frequency at which its reference atoms oscillate between two electronic energy levels. The new strontium clock is so precise it would neither gain nor lose one second in about 5 billion years, if it could operate that long. (This time period is longer than the age of the Earth, an estimated 4.5 billion years old.)
The strontium clock’s stability—the extent to which each tick matches the duration of every other tick—is about the same as NIST’s ytterbium atomic clock, another world leader in stability unveiled in August, 2013.*** Stability determines in part how long an atomic clock must run to achieve its best performance through continual averaging. The strontium and ytterbium lattice clocks are so stable that in just a few seconds of averaging they outperform other types of atomic clocks that have been averaged for hours or days.
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