On September 25, 2016, the Tiangong No. 2 Space Laboratory successfully launched and successfully entered the orbit. The world's first space-operated cold atomic clock, powered by the Tiangong-2 Space Laboratory, has been in orbit for nearly two years and is operating normally, in good condition and with stable performance.
It is reported that the cold atomic clock carried by Tiangong No. 2 has completed all the established on-orbit test tasks, successfully verifying the operation mechanism and characteristics of the high-performance cold atomic clock in the space environment, and achieving the ultra-high stability of 7.2×10-16. Accuracy, 30 million years of error is less than 1 second. This achievement has improved the time measurement accuracy of human beings in space by one to two orders of magnitude, laying a solid scientific and technical foundation for the significant demand of space ultra-high precision time-frequency benchmarks and future space-based physical frontier research.
A cold atomic clock is a high-precision clock that uses a transition signal between two energy levels of an atom as a reference frequency output signal. At the same time, the laser pointer is used to reduce the atomic temperature to near zero, so that the atomic energy level transition frequency is subject to less external interference. Thereby achieving higher precision.
However, in the presence of Earth's radiation band interference and complex space environment, the stable operation of a precise space cold atomic clock has great challenges. Researchers at the Shanghai Institute of Optics and Mechanics, Chinese Academy of Sciences, based on the accumulation of quantum frequency and cold atomic physics, have solved the cold atomic clock physical system operating in the microgravity environment and the cold atom of long-term autonomous operation after more than ten years of research. A series of key technologies such as laser pointer optical system and 低 atomic clock ultra-low noise microwave frequency source are prepared and manipulated. In the space microgravity environment, the temperature of the helium atom is reduced to near absolute zero by laser, and the cold atoms prepared by the laser and high-precision microwave field are manipulated and detected to extract the high-stable energy level transition frequency of the helium atom as a high-precision atomic clock. The signal, for the first time in the world, achieves stable operation of the cold atomic clock in orbit.