2021/01/31 by Jiu-Peng Chen, Chi Zhang, Yang Liu +16 · 1 citation
Physics and Astronomy · #quant-ph
paper · pdf · doi:10.1038/s41566-021-00828-5
published as Nat. Photonics 15, 570 (2021) · 32 pages, 8 figures
arxiv created 2021/01/31 · arxiv updated 2021/09/01
The basic principle of quantum mechanics guarantee the unconditional security of quantum key distribution (QKD) at the cost of inability of amplification of quantum state. As a result, despite remarkable progress in worldwide metropolitan QKD networks over the past decades, long haul fiber QKD network without trustful relay has not been achieved yet. Here, through sending-or-not-sending (SNS) protocol, we complete a twin field QKD (TF-QKD) and distribute secure keys without any trusted repeater over a 511 km long haul fiber trunk linking two distant metropolitans. Our secure key rate is around 3 orders of magnitudes greater than what is expected if the previous QKD field test system over the same length were applied. The efficient quantum-state transmission and stable single-photon interference over such a long distance deployed fiber paves the way to large-scale fiber quantum networks.