Vienna Team Claims Self-Regulating Thorium Atomic Clock

Researchers at the Vienna University of Technology claim to have developed a thorium-based atomic clock that regulates itself, according to hackaday.com. The team's source paper was published in Nature.

The clock works by using a laser to excite a thorium crystal, with the crystal's output then used to adjust the laser itself. If the laser drifts, the thorium nuclei absorb less light, shifting the output frequency to compensate.

That self-correcting behavior sets the design apart from prior atomic clocks, which need outside help to stay stable, the researchers say.

Why thorium

Scientists have long thought thorium could make an excellent clock because of the very narrow gap between two of its states, provided a laser can drive it. In early experiments, the laser's precise properties had to be supplied by another nuclear clock.

Optical atomic clocks are considered the leading approach for time standards.