Technology

BEIJING – China has transmitted an encrypted signal from a satellite using quantum key distribution technology, the international media have reported.

The achievement based on experiments conducted with the world’s first quantum satellite, Quantum Experiments at Space Scale (QUESS), was published in the authoritative academic journal Nature.

The Nature reviewers commented that the experiment was an impressive achievement, and constituted a milestone in the field, state-run Xinhua news agency reported.

Nicknamed “Micius,” after a 5th Century BC Chinese philosopher and scientist who has been credited as the first person ever to conduct optical experiments, the 600-kilogram- plus satellite was sent into a sun-synchronous orbit at an altitude of 500 kilometres on August 16, 2016.

Pan Jianwei, a lead scientist of QUESS and an academician of the Chinese Academy of Sciences (CAS), said the satellite sent quantum keys to ground stations in Xinglong, in north China’s Hebei Province, and Nanshan, near Urumqi, the capital of northwest China’s Xinjiang Uygur Autonomous Region.

The communication distance between the satellite and the ground station varies from 645 kilometres to 1,200 kilometres, and the quantum key transmission rate from satellite to the ground is up to 20 orders of magnitude more efficient than that expected using an optical fibre of the same length, said Pan.

When the satellite flies over China, it provides an experiment window of about 10 minutes. During that time, the 300 kbit secure key can be generated and sent by the satellite, according to Pan.