Chinese scientists have implemented twin-field quantum key distribution (QKD) through an 833-km optical fiber, setting a new world record in the field.
The system has tolerated a channel loss beyond 140 dB.
Furthermore, the optimized four-phase twin-field protocol and high-quality set-up make its secure key rate more than two orders of magnitude greater than previous records over similar distances.
The experiment, led by USTC (University of Science and Technology of China), is a solid step towards building reliable and efficient terrestrial quantum-secure networks over a scale of 1,000 kilometers.
The experiment results have been published recently in Nature Photonics, a peer-reviewed scientific journal under the Nature Publishing Group.