Optical clocks such as the aluminum ion, ytterbium, and strontium clocks have much higher resonance frequencies, high enough to be in the spectrum of light ... While a cesium clock may be off ...

Maybe that’s even more than half of the fun. [CuriousMarc] got an HP 5061A Cesium clock, a somewhat famous instrument as the model that attempted to prove the theory of relativity. The reason?

Atoms in an optical atomic clock are exposed to laser light. The atoms alter their quantum ... the clock is accurate to about ...

Atomic clocks are the basis upon which a second is defined. But there is a new kid on the block, the optical clock, which ...