We demonstrate the underwater quantum key distribution (UWQKD) over a 10.4-meter Jerlov type III seawater channel by building a complete UWQKD system with all-optical transmission of quantum signals, synchronization signal and classical communication signal. The wavelength division multiplexing and the space-time-wavelength filtering technology are applied to ensure that the optical signals do not interfere with each other. The system is controlled by FPGA, and can be easily integrated into watertight cabins to perform field experiment. By using the decoy-state BB84 protocol with polarization encoding, we obtain a secure key rate of 1.82Kbps and an error rate of 1.55% at the attenuation of 13.26dB. We prove that the system can tolerate the channel loss up to 23.7dB, therefore may be used in the 300-meter-long Jerlov type I clean seawater channel.
@article{arxiv.2106.13441,
title = {Experimental Demonstration of Underwater Decoy-state Quantum Key Distribution with All-optical Transmission},
author = {Yonghe Yu and Wendong Li and Yu Wei and Yang Yang and Shanchuan Dong and Tian Qian and Shuo Wang and Qiming Zhu and Shangshuai Zheng and Xinjian Zhang and Yongjian Gu},
journal= {arXiv preprint arXiv:2106.13441},
year = {2021}
}