Vienna team builds world's first self-stabilizing nuclear clock

Scientists in Vienna have built the world’s first self-stabilizing nuclear clock, a device that uses the nuclei of thorium atoms to keep time. Unlike previous prototypes that relied on conventional atomic clocks for stability, this new system maintains its own accuracy through an automatic feedback loop. The achievement, reported in the journal Nature, marks a significant step in precision metrology, though the clock does not yet surpass the performance of the world’s leading optical atomic clocks.

How the Nuclear Clock Works

Traditional atomic clocks measure time by tracking energy transitions in the electron shells of atoms. These electrons are sensitive to external disturbances, such as temperature changes or collisions, which can disrupt the clock's rhythm. The Vienna team, led by Prof. Thorsten Schumm at TU Wien and Prof. Ekkehard Peik at PTB Braunschweig, instead utilized the nucleus of the thorium-229 isotope.

Atomic nuclei are more than 10,000 times smaller than atoms, making them far less susceptible to environmental interference. Thorium-229 is unique because two of its nuclear energy states are separated by an unusually small energy gap. This allows researchers to trigger a transition between these states using laser light, a feat that was first demonstrated experimentally in April 2024.

The new clock operates by shining a laser onto a crystal containing thorium atoms. The laser’s frequency is tuned to match the specific resonance of the thorium nuclei. If the laser frequency drifts due to environmental factors, the amount of light absorbed by the nuclei decreases. The system detects this change and automatically adjusts the laser back to the correct frequency. "What you really want is a self-stabilizing nuclear clock," said Prof. Thorsten Schumm. "The basic idea is simple: you have a laser and you have thorium. The laser changes the energy state of the thorium nuclei, and the thorium nuclei are used to stabilize the frequency of the laser."

Performance and Precision

The researchers demonstrated that the clock could operate steadily for more than 24 hours without external intervention. During this period, the device achieved a relative precision of approximately 10 to the power of minus 15. This level of accuracy is equivalent to an error of roughly one second over 30 million years.

While this is a remarkable result for a first prototype, the clock is not yet as precise as the best optical atomic clocks currently in use. "This is not yet at the level of the world's best optical atomic clocks, but for a first prototype it is a fantastic result," said Schumm. The team identified that frequency reproducibility was limited to approximately 5 × 10⁻¹³ between different runs, likely due to local strain in the crystal structure. Future improvements in laser power and crystal quality are expected to enhance stability.

Implications for Science and Technology

The development of a self-stabilizing nuclear clock has implications beyond timekeeping. More accurate time measurement can improve the precision of other physical quantities, offering scientists new tools to investigate fundamental laws of nature. The technology could also support applications in satellite navigation, telecommunications, and financial systems, which rely on precise timing.

Additionally, the clock provides a new method for testing hypotheses in fundamental physics. In a companion study, researchers used the clock to search for effects predicted by models of ultralight dark matter. While no significant signal was found, the experiment placed upper limits on possible interactions, demonstrating the clock's potential as a sensitive detector for unknown physical phenomena.

Why it matters

This breakthrough validates a decades-old concept in physics: that atomic nuclei can serve as stable references for timekeeping. By decoupling the clock's stability from external atomic clocks, the Vienna team has created a self-sustaining system that is more robust against environmental noise. As the technology matures, nuclear clocks could eventually redefine the standard for measuring time, offering unprecedented precision for scientific research and global infrastructure.

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Sources

• sciencedaily.com: Scientists build a nuclear clock that could make atomic clocks obsolete | ScienceDaily
• thebrighterside.news: Scientists demonstrate sustained operation of the world's first self-regulating nuclear clock - The Brighter Side of News
• thenakedscientists.com: World’s first stand-alone nuclear clock | Interviews
• voi.id: Chinese Scientists Develop Nuclear Clock, Time Accuracy Potentially Overtakes Atomic Clock
• chitraltoday.net: Scientists Develop First Nuclear Clocks - Chitral Today
• timesofindia.indiatimes.com: For decades, scientists used Atomic clocks but world’s first stand-alone nuclear clock may change we measure almost everything - The Times of India

This article was drafted with AI assistance and checked against the sources above. Company claims are reported as claims. Cover image is AI-generated.