Chinese quantum satellite sends 'unbreakable' code

Any attempt to eavesdrop on quantum channel would introduce detectable disturbances to the system

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 on Thursday.
 
China launched the world's first quantum satellite last August, to help establish "hack proof" communications, a development the Pentagon has called a "notable advance".
 
The official Xinhua news agency said the latest experiment was published in the journal Nature on Thursday, where reviewers called it a "milestone".
 
The satellite sent quantum keys to ground stations in China between 645 km (400 miles) and 1,200 km (745 miles) away