International Researchers Successfully Develop the First Autonomous Thorium-229 "Nuclear Clock": Featuring Ultra-Strong Interference Resistance and a Fully Autonomous Closed-Loop Stable Operation Mechanism

Recently, the press office of TU Wien (Vienna University of Technology) announced that a team of scientists from Austria, Germany, and the Czech Republic has successfully developed the world's first nuclear clock based on the thorium-229 (chemical symbol ²²⁹Th) atomic nucleus. This nuclear clock possesses extremely high interference resistance and is capable of operating in a fully autonomous mode without external stabilization.

The research team stated that, compared with traditional atomic clocks that operate using entire atoms, timekeeping using atomic nuclei can theoretically achieve higher measurement precision. Two years ago, they successfully controlled the transition process of the thorium-229 atomic nucleus for the first time, but to achieve extremely high-precision timekeeping, it was still necessary to solve the problem of self-stabilization of the nuclear clock. Professor Thorsten Schumm of TU Wien pointed out that researchers are committed to overcoming this technical challenge.

It is understood that as early as half a century ago, physicists discovered the unstable isotope thorium-229, which exists in two forms, one of which has extremely low excitation energy. This characteristic not only makes observing its decay process extremely difficult, but also makes it an ideal basis for constructing an ultra-high-precision nuclear clock with high resistance to electromagnetic interference.

Two years ago, physicists from Austria and Germany developed a new method to measure time by observing the interaction between a laser beam and a specially prepared thorium crystal. However, the first version of this technology could not achieve fully autonomous operation, mainly due to the large size of the laser and its pulsed operation mode, which caused the device to rely on an external stabilization system.

Recently, German physicists successfully developed a compact solid-state laser capable of continuously producing highly stable radiation. This breakthrough enabled scientists to adjust the nuclear clock to a new operating mode, no longer tracking the light pulses generated by thorium-229 atoms, but instead monitoring changes in laser radiation intensity after interaction with the atomic nuclei of this element.

Preliminary experimental results show that the error rate of this nuclear clock is approximately 10 to the negative 15th power, equivalent to an error of about 1 second over roughly 30 million years. Although this precision is currently slightly lower than that of the best optical atomic clocks, scientists believe that through further improvement and optimization, they can significantly enhance the timekeeping precision of the nuclear clock and apply it to fields such as dark matter detection.