Overview
- Two independent teams reported functioning nuclear clocks that use calcium fluoride crystals doped with thorium-229 and an active feedback loop to lock a laser to the nuclear transition, turning earlier excitation demonstrations into an operational clock.
- The devices are proof-of-principle prototypes that do not yet match the best atomic clocks in raw stability, with current performance described as losing on the order of tens of seconds per billion years, but researchers say improvements to lasers, crystals and electronics should raise performance rapidly.
- One European team used their clock as a scientific probe to search for ultralight dark matter and reported sensitivity that rivals or exceeds atomic clocks for certain types of measurements, though no dark-matter signal was found.
- The solid-state, room-temperature approach reduces sensitivity to stray electromagnetic fields and removes the need for bulky vacuum systems, which could make future nuclear clocks more compact and robust than today's atomic clocks.
- Both results are reported as preprints on arXiv and have not yet been peer reviewed, and teams outline clear development paths that could affect navigation, communications and laboratory tests of fundamental constants if the technology is refined and validated.