This Is the Most Accurate Clock in the World

An experimental clock in Colorado has set new world records in precision and stability.

A research group at JILA—a joint institute of the University of Colorado Boulder and the National Institute of Standards and Technology—unveiled a strontium atomic clock that has crushed previous records of timekeeping by achieving 50 percent greater accuracy.

JILA’s experimental atomic clock based on strontium atoms held in a lattice of laser light is the world’s most precise and stable atomic clock. This image is a composite of many photos taken with long exposure times. (Credit: Ye group and Brad Baxley/JILA)

Precision refers to how closely the clock approaches the true resonant frequency at which its reference atoms oscillate between two electronic energy levels, and stability is the extent to which each tick matches the duration of every other tick.

Announced in a paper in the journal Nature, the JILA strontium lattice clock is 50 percent more precise than the record holder of the past few years, NIST’s quantum logic clock.

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. The University of Colorado Boulder release explained:

In JILA’s world-leading clock, a few thousand atoms of strontium are held in a column of about 100 pancake-shaped traps called an optical lattice formed by intense laser light. JILA scientists detect strontium’s “ticks” (430 trillion per second) by bathing the atoms in very stable red laser light at the exact frequency that prompts the switch between energy levels.

To check the performance, the JILA team compared two versions of the strontium clock, one built in 2005 and the other just last year. Both clocks have set previous records of various types. In the latest work, the two clocks fully agreed with each other within their reported precision—demonstrating the ability to make a duplicate copy and maintain the performance level.

Complex enough for you? The international timekeeping community isn’t convinced yet.

The current international definition of units of time requires the use of cesium-based atomic clocks, such as the current U.S. civilian time standard clock, the NIST-F1 cesium fountain clock. So, only cesium clocks are ‘accurate’ by timekeeping standards, even though the strontium clock has better precision.

The strontium lattice clock operates at optical frequencies, much higher than the microwave frequencies used in cesium clocks. But, because it has achieved such marked improvements in precision and stability, this NIST/JILA strontium clock may eventually change the international timekeeping standards.

NIST’s cesium fountain clock uses microwave frequencies; the current international definition of units of time requires the use of cesium-based atomic clocks but the experimental strontium clock is 50 percent more precise (Credit: NIST)

This doesn’t mean your watch will keep better time, but the atomic clocks could be used to help develop incredibly precise quantity sensors for gravity and temperature, generally providing researchers with a way to measure minute quantities in more detail than ever before, the Verge reported.

“We already have plans to push the performance even more,” NIST/JILA Fellow and group leader Jun Ye, said. “So in this sense, even this new Nature paper represents only a ‘midterm’ report. You can expect more new breakthroughs in our clocks in the next 5 to 10 years.”

Check out how the strontium clock works below.

(H/T: The Verge)

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