China’s quantum satellite sends hack-proof code from space


China has sent an unbreakable code from its Quantum Experiments at Space Scale (QUESS) satellite to Earth, representing the first step in developing a ‘hack-proof’ global quantum communication network.

The country sent QUESS, the world's first quantum satellite, into a Sun-synchronous orbit last August.

The latest achievement is based on the experiments conducted with QUESS, which sent quantum keys to ground stations in Xinglong and Nanshan, China.

According to QUESS lead scientist and Chinese Academy of Sciences (CAS) academician Pan Jianwei, the communication from the satellite to the ground stations occurred over a distance between 645km and 1,200km.

“Satellite-based quantum key distribution can be linked to metropolitan quantum networks where fibres are sufficient and convenient to connect numerous users within a city over 100km."

The quantum key transmission rate between the satellite and the ground was up to 20 orders of magnitude more efficient than an optical fibre of the same length.

The 300kB secure key can be generated and transmitted during the 10min experiment window, which is opened when QUESS flies over China.

Pan said: “That, for instance, can meet the demand of making an absolute safe phone call or transmitting a large amount of bank data.

“Satellite-based quantum key distribution can be linked to metropolitan quantum networks where fibres are sufficient and convenient to connect numerous users within a city over 100km.

“We can thus envision a space-ground integrated quantum network, enabling quantum cryptography, most likely the first commercial application of quantum information, useful at a global scale.”

Pan further noted that quantum entanglement, which is the key technology used in quantum communications, has the potential to prevent wiretapping and enable secure communication.

In the event of snooping, the eavesdropper will end up disturbing the quantum channel and can be detected by the communicating users.