Researchers at TU Wien in Vienna and Germany's Physikalisch-Technische Bundesanstalt tested a prototype clock that uses thorium nuclei held in a crystal.
The system uses feedback from the nuclei to keep its laser tuned to the right frequency, allowing the clock to stabilize itself rather than needing a person to make each adjustment.
During a one-day test, the prototype remained stable for more than 24 hours. TU Wien reports a precision of about one second in 30 million years, but says the prototype is not yet as precise as the best optical atomic clocks.
The team says stronger lasers and improved crystals could help the technology advance. The work was published in the journal Nature.
