China built ultra-precise clock

By Alimat Aliyeva

Scientists from the University of Science and Technology of China (USTC) have made an important breakthrough in the field of quantum metrology by developing a new generation of strontium optical clocks. These devices can measure the passage of time with an accuracy that was previously considered almost impossible. The clock is so stable that its error would be less than one second over a period twice the age of the universe, AzerNEWS reports.

How was such accuracy achieved?

A group of researchers led by Zhi-Peng Jia demonstrated the operation of the USTC Sr1 optical clock, whose systematic uncertainty is only 9.2 × 10?¹?. This achievement places the Chinese device on the same level as the most advanced clocks developed by leading institutions such as the U.S. National Institute of Standards and Technology (NIST). It may also open the way to redefining the international definition of the second in the SI system of units.

The main component of the system is strontium-87 atoms, which are trapped in a one-dimensional optical lattice created by laser light. Their quantum state is measured using an ultra-stable laser with a wavelength of 698 nanometers. To reach this extreme level of precision, scientists developed innovative techniques to reduce factors that normally distort atomic oscillations. One of the most difficult challenges was eliminating the light shift caused by the optical lattice.

Special attention was also given to magnetic effects. By using magnetically insensitive atomic transitions, researchers reduced the influence of external magnetic fields by more than 22 times compared with traditional methods. Careful calibration allowed the team to minimize errors caused by magnetic shifts. As a result, the system demonstrates remarkable frequency stability, proving that the clock can operate reliably for extremely long periods.

Why is this important?

The capabilities of such devices go far beyond simply measuring time. Thanks to their extraordinary sensitivity to gravitational potential, optical clocks like the Sr1 can be used in relativistic geodesy—a technique that allows scientists to measure differences in height with millimeter-level precision by detecting tiny variations in gravity.

This technology could help monitor tectonic plate movements, groundwater changes, and volcanic activity, providing new tools for studying Earth’s dynamic processes.

In addition, ultra-precise optical clocks may play an important role in fundamental physics. Scientists hope to use them to search for dark matter, detect low-frequency gravitational waves, and measure extremely small variations in fundamental physical constants. Some researchers even suggest that networks of optical clocks placed around the world could act as a new type of planet-scale sensor, capable of detecting subtle changes in space-time itself.