Scientists make quantum leap towards a secure new kind of internet
A global quantum internet is a major step closer as satellite beams ‘entangled’ light particles to ground stations more than 700 miles apart
By Ian Sample
Jun 15 2017
Scientists have taken a major step towards building a global quantum internet by beaming “entangled” particles of light from a satellite to ground stations more than 700 miles apart.
The feat paves the way for a new kind of internet which draws on the curious ability for subatomic particles to be connected to one another despite being far apart and even on opposite sides of the planet.
Researchers believe that by linking particles together in this way, encrypted information could be sent from place to place across a quantum network with no danger of it being decrypted and read by others, as can be done on the existing internet.
Jian-Wei Pan, who led the research at the University of Science and Technology in Hefei in China, said the demonstration was a moment he had been dreaming of since 2003. “Many people thought it was a crazy idea, because it was very challenging,” he said.
The work obliterates the previous world record for sending pairs of photons that are connected to one another by a strange rule of quantum physics first spotted by Einstein. Until now, the farthest researchers had ever sent entangled photons stood at a mere 65 miles, less than one tenth of the distance achieved in the satellite experiment.
“It’s a first step, and a major step, toward creating a global quantum network,” said Pan. “All the previous methods are limited to about 100km so can only work within a city.”
The experiment relied on the world’s first quantum-enabled spacecraft: a Chinese satellite called Micius. As it soared over China, the satellite created pairs of photons with properties that were linked through quantum entanglement. It then beamed these simultaneously to ground stations in Delingha, Lijiang and Nanshan. Each pair of particles travelled up to 1,240 miles before they reached their destinations. Details of the study are published in Science.
Pan said that the kind of cryptography used to keep data safe today relies on complex mathematics which can often be defeated by hackers. “If a future quantum network is established, the security is ensured by the laws of physics, which are unconditionally secure,” he said. “It will be beneficial for all human beings.”