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.
