China's quantum satellite sends 'unbreakable' code

Professor Pan Jianwei, from the Chinese Academy of Sciences, at a news conference last Friday. The technology, which some have called a "milestone", could have applications in communications for defence and finance.
Professor Pan Jianwei, from the Chinese Academy of Sciences, at a news conference last Friday. The technology, which some have called a "milestone", could have applications in communications for defence and finance.PHOTO: XINHUA

BEIJING • China has sent an "unbreakable" code from a satellite to the Earth, marking the first time space-to-ground quantum key distribution technology has been realised, state media said yesterday.

China launched the world's first quantum satellite in August last year, to help establish "hack-proof" communications. The official Xinhua news agency said the latest experiment was published in the journal Nature yesterday, where reviewers called it a "milestone".

Nicknamed "Micius", after a fifth century BC Chinese philosopher and scientist credited as the first person to conduct optical experiments, the 600kg satellite sent quantum keys to ground stations in China between 645km and 1,200km away.

This was done at a transmission rate up to 20 orders of magnitude more efficient than an optical fibre, said Professor Pan Jianwei, lead scientist on the experiment from the state-run Chinese Academy of Sciences.

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

Any attempt to eavesdrop on the quantum channel would introduce detectable disturbances to the system, he added. "Once intercepted or measured, the quantum state of the key will change, and the information being intercepted will self-destruct," said Prof Pan.

State media said there were "enormous prospects" for applying this new generation of communications in defence and finance.

REUTERS, XINHUA

A version of this article appeared in the print edition of The Straits Times on August 11, 2017, with the headline 'China's quantum satellite sends 'unbreakable' code'. Print Edition | Subscribe