China Builds First Space-to-ground integrated quantum network

With the help of Micius it establishes intercontinental video with Australia.

September 29th President BAI Chunli of the Chinese Academy of Sciences in Beijing and President Anton Zeilinger of the Austria Academy of Sciences in Vienna held the first quantum-secure video meeting which was the first presentation of intercontinental quantum communication.


Private and safe communication is basic human requirement. Specifically, with the increasing usage of Internet and online business, it is of fundamental significance to set up a safe system with worldwide information safety. Conventional open key cryptography normally depends on the observed mathematical difficulty of some mathematical functions. As opposed to that, quantum key dispersion (QKD) utilizes singular light quanta (one photon) in quantum superposition stages to ensure unrestricted safety between persons on great remoteness. Hitherto, the quantum communication remoteness had been constrained to a couple of hundred kilometers, because of the channel loss of threads or earth free space. A hopeful answer to this issue is using satellite and space-based connection, which can appropriately link two distant places on the Earth with significantly diminished channel loss since the majority of the photons’ promulgation route is in vacuum with insignificant loss and inconsistency.

An interdisciplinary group of researchers from different institutes from the Chinese Academy of Sciences, headed by Professor PAN Jianwei, were working over one decade on building up a complex satellite, named Micius, intended for quantum science tests, which was launched with success led on sixteenth August 2016, from Jiuquan, China, circling at a height of ~500 km . The satellite has 3 cargoes: a bait state QKD transmitter, an entangled photon source, and a quantum teleportation receiver and analyzer. Five stations on Earth are constructed in China to work jointly with the Micius, situated in Xinglong (close Beijing, 40°23’45.12”N, 117°34’38.85”E, height 890m), Nanshan (close to Urumqi, 43°28’31.66”N, 87°10’36.07”E, height 2028m), Delingha (37°22’44.43”N, 97°43’37.01″E, height 3153m), Lijiang (26°41’38.15”N, 100°1’45.55”E, height 3233m), and Ngari in Tibet (32°19’30.07”N, 80°1’34.18”E, height 5047m).

During the year since the launch, three indicators that will be crucial to a worldwide quantum network have been accomplished: satellite-to-ground bait state QKD with kHz degree over a remoteness of ~1200 km (Liao et al. 2017, Nature 549, 43); satellite-based bait dispersion to two places on the Earth distanced ~1200 km and Bell test (YIN et al. 2017, Science 356, 1140), and ground-to-satellite quantum transportation (REN et al. 2017, Nature 549, 70). The performance of the connection in the satellite-based QKD was evaluated to be ~20 requests of sizes bigger than straight transmission through optical threads at the identical distance at 1200 km.

The satellite-based QKD has now been connected with city quantum systems, where with the help of threads big number of clients is linked in a city at a remoteness of ~100 km. For instance, the Xinglong station has now been linked with the city multi-node quantum system in Beijing by means of optical fibers. Newly, the biggest fiber-based quantum connection pillar has been constructed in China by Professor PAN’s staff, connecting Beijing to Shanghai (passing through Jinan and Hefei, and 32 reliable transfers) with a fiber spanning 2000 km. The pillar utilizes bait state protocol QKD and reaches an all-pass safe key degree of 20 kbps. It is on probe for acutal applications by government, banks, securities and insurance agencies.

Micius can be furthermore used as a reliable transmitter to link any two places on the earth for high-safety key interchange. At the beginning of the year, the Chinese scientists have carried out satellite-to-ground QKD in Xinglong. Then, the safety keys were put in the satellite for 2 hours when it achieved Nanshan station close to Urumqi, ~2500 km remote from Beijing. By carrying out one more QKD between the satellite and Nanshan station, and utilizing single -pad encrypting, safety key between Xinglong and Nanshan were then founded. In order to examine the strength and flexibility of the Micius, QKD from the satellite to Graz ground station close Vienna has been implemented effectively this June, as a joint effort between Professor PAN and Professor Anton Zeilinger’s team. On demand, other future tests like that are intended amongst China and Singapore, Italy, Germany, and Russia.


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