Abstract
There is a growing interest in the security of underwater communication with the increasing demand for undersea exploration. In view of the complex composition and special optical properties of seawater, this paper deals with a performance analysis for continuous-variable quantum key distribution (CVQKD) over an underwater link. In particular, we focus on analyzing the channel transmittance and detection efficiency based on Monte Carlo simulation for different water types, link distances and transceiver parameters. A comparison between the transmittance obtained by simple Beer’s law and Monte Carlo simulation reveals that the transmittance of underwater link may be severely underestimated in the previous underwater CVQKD research. The effect of the receiver aperture and field of view (FOV) on detection efficiency under different water types is further evaluated based on Monte Carlo. Simulation results show that the transmission distance of the underwater CVQKD system obtained by Monte Carlo simulation in pure sea water, clear ocean water and coastal ocean water is larger than that obtained by Beer’s law, while the key rate of the system in all types of water is smaller than that obtained by Beer’s law because the size and FOV of the receiver aperture are taken into account. By considering the practical system parameters, this paper establishes a comprehensive model for evaluating the security of underwater CVQKD systems with different system configurations.
Highlights
Underwater communication [1] has attracted much attention in recent years driven by the ever-increasing demand for ocean exploration and investigation
For the cases of clear ocean water, coastal ocean water, and turbid harbor water, the results of Beer’s law are much smaller than the results of Monte Carlo simulation, which is due to the scattering coefficient of these water types is higher than pure sea water, and a significant part of scattered photons may still be received by the receiver, while Beer’s law considers all the scattered photons to be lost
The solid lines correspond to the transmittance obtained by Monte Carlo simulation, and the dashed lines correspond to the transmittance obtained by Beer’s law
Summary
Underwater communication [1] has attracted much attention in recent years driven by the ever-increasing demand for ocean exploration and investigation. Some analyses on underwater free space CVQKD have presented by researchers, such as channel parameter estimation for satellite-to-submarine links [20], security simulation for different kinds of seawater [21], and performance improvement via photon substraction [22]. All these studies used the well-known Beer’s law to model the attenuation effects of the seawater due to its simplicity. By comprehensively considering the practical system parameters, this Monte Carlo-based model provides a feasible way to estimate the performance of various CVQKD systems with different system configurations
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