Photon loss in optical fibers prevents long-distance distribution of quantum information on the ground. Quantum repeaters have been proposed as a means of overcoming the problem, but communication distance is still limited because of the complexity of the system. Alternative solutions include transportable quantum memory and quantum-memory-equipped satellites, where long-lived optical quantum memories are key components in realizing global quantum communication. Until recently however, it had not been possible to store optical memories demonstrated for longer than a minute.
A research team led by academician Guo Guangcan of the University of Science and Technology of China, has developed high-performance solid quantum memory based on rare-earth ion-doped crystals that successfully increased the coherent storage of light to an hour, paving way for future large-scale quantum communication based on long-lived solid quantum memories. The results were published in the journals Nature Communications and Nature on April 22 and June 2, respectively.