China news service, Beijing, Oct. 11 (xinhua The 2019 national time and frequency academic conference was held in Beijing on oct 10, solstice, 11. Zhang shougang, director of the national timing center of the Chinese Academy of Sciences, said at the meeting that China will build a unique three-dimensional cross-timing system in the next five years, and there are no similar plans in the world.
The system is mainly composed of beidou navigation satellite system, the space station time-frequency experiment system, ground-based optical fiber timing system and ground-based long-wave timing system, zhang said. The beidou satellite navigation system covers the whole world with a timing accuracy of 10 nanoseconds (1 nanosecond is equal to a billionth of a second). The space station's time-frequency experiment system will use optical frequency atomic clocks to provide coverage in picoseconds (a picosecond is a trillionth of a second). Ground-based optical fiber timing network is connected to important nodes in China with a timing accuracy of 100 picoseconds, which will be the highest precision and longest distance optical fiber timing network in the world. The ground-based long wave timing covers the whole country, and the timing accuracy in important areas is better than 100 nanoseconds.
In daily life and work, when users' time is deviated, they will try to find a standard time for calibration. The standard time in China is broadcast by the national timing center of the Chinese Academy of Sciences where zhang shougang works.
"Punctuality" is the premise of timing, which means continuous generation and maintenance of time. The core instrument and equipment are punctuality atomic clock and reference atomic clock. Reference clock is a national or regional precision of the highest time frequency standard device. Zhang told reporters that around 2026, international discussions will be held on whether to replace the cold atomic microwave clock with an optical frequency atomic clock to form a new reference clock. Currently, optical frequency atomic clocks are nearly three orders of magnitude better than microwave clocks.
"In the future, the application of nuclear atomic clocks and quantum time transmission is expected to provide more accurate time." Zhang shougang said that China's quantum entanglement time synchronization technology is still relatively advanced in the world, at the international advanced level. At present, Chinese scholars have achieved tens of femtoseconds (one femtosecond is a quadrillion of a second) through time transmission with frequency entangled over a range of several kilometers.
In this meeting, zhang shougang, wang lijun and other 10 experts won the outstanding contribution award. It is reported that the national time frequency academic conference is the most professional time frequency field, the largest, the highest academic level, the latest scientific research results of the time frequency technical exchange conference, held every two years, has been held 16 sessions.