Thorium Clocks Start Ticking with Lasers

Atomic clocks are super accurate. But, unsurprisingly, some atomic clocks are better than others, depending on your definition of better. Researchers at Vienna University claim to have a superior thorium-based ….

Thorium Clocks Start Ticking with Lasers. It isn’t necessarily more accurate than other atomic clocks, but it is self-regulating. Apparently, prior atomic clocks need help to stay stable.

But scientists have thought that thorium, with its very narrow gap between two states, would make an excellent clock with the help of a laser. The laser has to have precise properties that, at least in early experiments, were. Obviously, you’d like to be able to use a laser to excite the source — a thorium crystal in this case — and then use the output of that to adjust the laser.

If the laser drifts, the thorium nuclei absorb less light, and that adjusts the output frequency to compensate.