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The Chinese satellite Micius has been used to establish a successful quantum communication link between China and Russia.
This has made it possible to exchange ultra-secure messages between ground stations in Russia and China, thousands of kilometres apart.
Quantum computers could pose a threat to classical encryption schemes such as RSA, being well suited to cracking them through brute force. This has spurred efforts to develop new quantum-proof approaches to secure communications, including quantum key distribution (QKD). QKD allows cryptographic keys, which are generated from a sequence of polarised photons, to be shared in a way that makes it physically impossible to eavesdrop without being detected.
Photons can be transmitted via optical fibre – an approach appropriate for municipal networks – although signal degradation limits individual spans to the hundreds of kilometres at most. Transmitting photons through space, using specialised satellites, makes it possible to establish quantum communication channels over much greater distances.
In 2017, Chinese scientists announced that they had used their Micius satellite (which was launched the year before) to implement QKD across 1,200km in a major milestone for quantum communications. China is recognised as the world leader in this technology.
According to the South China Morning Post, the latest development involved using keys transmitted by Micius to establish an ultra-secure link between the Zvenigorod observatory near Moscow and the Nanshan ground station near Urumqi in China’s western Xinjiang province. The two ground stations are 3,800km apart. The scientists used a quantum key shared during the experiment to encrypt and decrypt two messages: a quote from the Chinese philosopher for whom the Micius satellite was named, and an equation from the Soviet physicist Lev Landau.
Alexey Fedorov of Russia’s National University of Science and Technology and the Russian Quantum Centre – two institutions at the forefront of Russian efforts to develop quantum technologies – told the newspaper that this first “full cycle” test between the two countries was conducted last year.
He said that “technically, it’s absolutely possible” to build a quantum communication network between BRICS nations (Brazil, Russia, India, China and South Africa). He added that Russia was experimenting with the aim of launching its own quantum satellite, having previously done work on a quantum microsatellite prototype.
Quantum technologies are considered strategically important, with many countries pouring funding into their development. Last year, Russian president Vladimir Putin said at the Future Technologies Forum in Moscow that quantum technologies would have an important role to play in Russia’s digital infrastructure. Russia has also proposed joint efforts to advance future technologies (including quantum technologies) with fellow BRICS nations.
