New Optical Atomic Clock Has Heart Smaller Than a Coffee Bean

What that means is that its light undulates 385.285 trillion times per second. That's too fast for modern electronics to count so the optical clock uses two components called frequency combs.

Mounted on tiny chips, these combs translate the laser’s high-frequency optical ticks into slower, widely-used, countable ticks. The optical clock ultimately produced ticks paced at 22 gigahertz, 50 times better than the current cesium-based chip-scale clocks. 

Remarkable accuracy

"Laboratory optical atomic clocks achieve remarkable accuracy (now counted to 18 digits or more), opening possibilities for exploring fundamental physics and enabling new measurements. However, their size and the use of bulk components prevent them from being more widely adopted in applications that require precision timing," write the researchers in their new paper. 

But before you get too excited, envisioning an extremely efficient pocket watch, it should be noted that the clock is hooked up to supporting electronics that fill two tables. The new clock might be tiny compared with its predecessors, but it still has a long way to go.

Still, its new chip-based heart requires very little power (just 275 milliwatts) and, with additional advances, could potentially be made small enough to be handheld. "These results demonstrate key concepts of how to use silicon-chip devices in future portable and ultraprecise optical clocks," write the researchers.

“We made an optical atomic clock in which all key components are microfabricated and work together to produce an exceptionally stable output,” NIST Fellow John Kitching said. “Ultimately, we expect this work to lead to small, low-power clocks that are exceptionally stable and will bring a new generation of accurate timing to portable, battery-operated devices.”  

The study is published in Optica.