2019 the National Conference on time and frequency was held in Beijing in from October 10th to 11th. Zhang Shougang, director of the national time service center of the Chinese Academy of Sciences, said at the meeting that in the next 5 years, China will build a unique intersecting time service system to provide high-precision time service for China's economic and military development.

The system is mainly composed of 4 parts, which are mutually reinforcing and mutually reinforcing, including the high precision time and frequency experimental system of China space station, Beidou satellite navigation system, ground-based optical fiber timing system and ground-based long wave time service system. The timing of the Beidou satellite navigation system is about 10 nanoseconds (1 nanoseconds equal to 1/1000000000 seconds). The ground-based optical fiber time service covers all the important nodes in the country. The timing accuracy is 100 picoseconds (1 picoseconds equals one trillion seconds). It will be the world's highest precision and longest distance optical fiber time service network.It is better than 100 ns, and it also broadcasts satellite time difference information to improve satellite timing accuracy.

Zhang Shougang said that the current timing is mainly for the ground or near ground space. With the expansion of the scope of national interests, deep space and underwater time service technology will become an important part of exploration and development.

Zhang Shougang said, "In the future, nuclear atomic clock and quantum time transfer are expected to be applied and provide more accurate time." Quantum entanglement used for information transmission has many manifestations, such as polarization entanglement and amplitude entanglement. Quantum time transfer and synchronization applications are frequency entanglement. China's quantum entanglement time synchronization technology is relatively leading all over the world, and is at the international advanced level.

At present, Chinese scholars transmit tens of femtosecond times through frequency entanglement in a few kilometres. (1 femtosecond is equal to ten million 1/100000000 seconds). At the international advanced level.