Chinese scientists say they have succeeded in an experiment that could improve satellite navigation and redefine the second as a unit of time, reports the South China Morning Post.
The scientists performed the experiment in Urumqi, capital of Xinjiang Uygur autonomous region in western China. They placed two terminals in laboratories 113 km (70 miles) apart. Each terminal was equipped with a laser, a telescope and two optical frequency combs that measure exact frequencies of light. Laser pulses sent between the terminals allowed researchers to confirm the time.
The research team was led by quantum physicist Jian-Wei Pan at the University of Science and Technology of China (USTC).
Sending signals over long distances would enable a global network of optical clocks that can help improve the accuracy of satellite navigation services.
China also is sending three atomic clocks to its Tiangong space station to establish a space-based timekeeping system of exceptional accuracy. The clocks can work together to measure time with 10-19 stability, missing only one second every few billion years, and is expected to be thousands of times more accurate than a hydrogen maser.