Research on Underwater Measurement-Device-Independent Quantum Key Distribution

Focusing on the application scenario where the underwater mobile platforms wirelessly access the cabled underwater information networks to achieve communication, an underwater access scheme for measurement-device-independent quantum key distribution is proposed to ensure communication security. Based on the analysis of the optical characteristics of the seawater channel, an underwater access model of measurement-device-independent quantum key distribution is constructed, simulated and analyzed to verify the feasibility and effectiveness of the scheme. The simulation results show that the maximum secure access distance of the scheme (under extreme conditions) can be extended from 147 meters to 230 meters or even 451 meters as the seawater type changes from turbid seawater to moderately turbid seawater to clear seawater. The vacuum + weak decoy state scheme can obtain performance that is very close to this limit. After considering the effect of finite data-set size, the performance of the scheme is reduced, but it can still meet the application requirements of underwater mobile platform access within a certain range. In practical applications, measures such as deploying wired communication buoys at network nodes can be used to further expand the effective access range.