China is developing a quantum communications satellite network

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HELSINKI — Chinese research institutes are working to construct a quantum communications network using satellites in low and medium-to-high Earth orbits.

Pan Jianwei, a scientist with the Chinese Academy of Sciences (CAS) and a member of the member of the 14th National Committee of the Chinese People’s Political Consultative Conference (CPPCC), made the comments in an interview with media March 4 on the sidelines of China’s annual political sessions in Beijing.

“We are cooperating with the National Space Science Center to develop a medium-to-high Earth orbit satellite. In the future, the combination of high orbit satellites and low Earth orbit satellites will build a wide-area quantum communication network,” Pan said, according to Yicai Global.

The network would use elements of quantum mechanics for encryption and secure transmission of information.

The plan builds on breakthroughs made by China’s 2016 Quantum Science Satellite, also known as Mozi, or Micius. The mission, led by Pan, carried out experiments in quantum key distribution (QKD), quantum entanglement distribution and quantum teleportation.

Reports of Pan’s comments did not provide further details of the planned network, but earlier publications provided insight.

A first step will see three or five small satellites focused on QKD—generating entangled particles for use as quantum keys—with masses under 100 kilograms. They will be sent into sun-synchronous orbits (SSO) at altitudes of 800 kilometers, according to a 2022 paper authored by Pan and others at CAS and the University of Science and Technology of China (USTC).

LEO satellites would provide links between cities, while satellites in higher orbits would allow intercontinental quantum communication.

CAS, USTC and others collaborated on the Jinan-1 satellite launched in 2022 on a Lijian-1 rocket, operated by a launch spinoff from CAS. The satellite is the first apparent test QKD satellite for the LEO network and demonstrated a miniaturization of key technologies.

The initial higher orbit satellite, earlier referred to as the “MEO-to-GEO satellite”, will allow for longer duration tests, as satellites in LEO or SSO pass overhead in a matter of minutes. It will carry a 600 mm diameter telescope for photon transmission.

The higher orbit satellites will allow the creation of a global, all-day quantum communication network.

China has also been building compact ground stations for the network. This has so far allowed demonstrations of quantum communications between the Mozi satellite and the cities of Beijing, Jinan, Weihai, Lijiang and Mohe.

China in recent years included quantum communications and quantum computing in a list of technological megaprojects for breakthroughs by 2030 and has been noted as a strategic emerging industry.

The European Space Agency is also looking to develop a quantum communications network, while governments including the US and United Kingdom are also collaborating in this area. The 2016 Mozi mission was developed by CAS and its NSSC institute as part of a first round of Chinese space science missions. Second and third rounds of missions are now being developed and considered by CAS.

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