Vienna team builds first self-stabilizing nuclear clock

Researchers at TU Wien led by Prof. Thorsten Schumm have built the first self-stabilizing nuclear clock, which holds its own frequency without relying on a conventional atomic clock. The thorium-229 device ran for over 24 hours at a relative precision of about 10⁻¹⁵, equivalent to one second over 30 million years.

• Thorium-229 nuclear clock stabilizes its laser frequency without an atomic clock reference
• Relative precision of about 10⁻¹⁵, or one second over 30 million years
• The clock ran unattended for more than 24 hours
• Precision is below the best optical atomic clocks, but it is a first prototype