First-in-history: Chinese scientists achieve quantum entanglement over 420km distance
What's the story
Chinese scientists have set a new record in the field of quantum entanglement by successfully entangling cold atoms over a distance of 420km. The achievement is more than four times longer than any previous attempts and surpasses the limits of direct transmission due to fundamental physical constraints. The research was published in the peer-reviewed journal Physical Review Letters.
Future implications
Major step toward development of intercity quantum networks
The successful entanglement experiment is seen as a major step toward the development of intercity quantum networks.
"Our experiment provides a test bed for studying quantum-network applications beyond the metropolitan scale," said the team of physicists, who included Pan Jianwei from the University of Science and Technology of China in Hefei, Anhui province.
The team used two quantum memory units, each made up of laser-cooled clouds of rubidium atoms, separated by 420km and linked via an optical fiber connection.
Scientific challenge
What is quantum entanglement?
Quantum entanglement is a complex phenomenon where two or more particles, usually photons, become inextricably linked.
They share a joint quantum state irrespective of the distance separating them.
While scientists have previously achieved this with light particles over long distances in space and through optical fiber, adding quantum memory to the mix complicates the process even further.