海洋气泡对水下量子通信性能的影响

Effect of Marine Bubbles on the Performance of Underwater Quantum Communication Channel

随着水下无线通信的发展,关于海洋环境量子通信的研究也逐渐成为热点。其中,研究海洋气泡对光量子在水下传输的影响具有重要意义。为了研究海洋气泡对水下量子通信信道性能的影响,根据海洋气泡的粒径分布模型,研究了气泡的散射特性,并根据气泡的消光系数,分析了不同条件参数对链路衰减、纠缠度、信道容量以及信道误码率的影响,并进行了仿真实验。结果表明:气泡浓度和传输距离的增大,使链路衰减和误码率增加,对于幅值阻尼信道、退极化信道和比特翻转信道,其信道容量均有所减小;随着气泡半径的增大、深度的减小,信道纠缠度降低。由此可见,海洋气泡对量子通信性能的影响不可忽略,在实际应用中为了保障水下量子通信的传输效率,应适当调节水下量子通信相关参数,减小海洋气泡环境对通信系统的影响。

Objective In recent years,quantum communication has become a research hotspot in China and abroad for its better data transmission security.As the core of the quantum information theory,quantum communication can be more secure and reliable for information transmission and is an important direction of inquiry.With the development of underwater wireless communication,it is important to research underwater quantum communication for marine and military fields.Bubbles are ubiquitous in the ocean,and the scattering and refraction effects of bubbles on light can cause certain losses in optical quantum transmission,which exerts a certain impact on the performance of underwater optical quantum communication.However,the research on the effect of bubbles on the channel performance of underwater quantum communication has not been conducted.By building the particle size distribution and scattering coefficient models of marine bubbles,the paper analyzes the effects of different condition parameters on link attenuation,entanglement,channel capacity,and channel bit error rate(BER)in the marine bubble environment to investigate the influence of these bubbles on the channel performance of underwater quantum communication.This is of great significance to improve the efficiency of underwater quantum communication.Methods Marine bubbles are mainly generated by wind-driven wave breaking.With an aim to study the influence of marine bubbles on the channel performance of underwater quantum communication,the particle size distribution function of the bubbles is firstly derived and established.The scattering characteristics and extinction coefficient of the bubbles are studied according to the particle size distribution model of marine bubbles.Additionally,according to the extinction characteristics,the relationship between marine bubble parameters and link attenuation is firstly established,and then the effects of different depths and bubble radi on channel entanglement are analyzed.Then,the effects of different bubble concentrations and transmission distances on three channel capacities of amplitude damped channel,depolarized channel.,and bit-flip channel are analyzed respectively.Finally,the effects of different bubble concentrations and transmission distances on channel BER are studied and analyzed.At the same time,the effects of different bubble concentrations and transmission distances on the channel BER are studied and simulated.The theoretical analysis and simulation results can provide a reference for the design of underwater quantum communication in the marine bubble environment.Results and Discussions The simulation results show that the density of bubbles decreases with the increasing depth from the sea level,whereas increases with the rising wind speed.The scattering coefficient of bubbles has the same trend as the bubble density number under the same parameter conditions.Under short transmission distance and small bubble concentration,the link attenuation caused by marine bubbles is also small.With the increase in the transmission distance of optical quantum signals and the bubble concentration,the link attenuation grows rapidly.The channel entanglement increases with the rising depth from the sea level and the decreasing bubble radius.For the amplitude damping channel,depolarization channel,and bit-flip channel,the channel capacity decreases to different degrees with the increasing transmission distance and bubble concentration.The capacity of the depolarization channel and the bit-flip channel is more affected by the transmission distance,and the transmission distance exerts less effect on the channel capacity.The BER in the marine bubble environment is also affected by the transmission distance and bubble concentration.When the bubble concentration is small with a short transmission distance,the system BER changes slowly.When the bubble concentration is large with a long transmission distance,the optical quantum signal attenuates seriously and the BER value rises rapidly.Conclusions To investigate the effect of marine bubbles on the channel performance of underwater quantum communication,this paper studies the scattering characteristics of the bubbles according to the particle size distribution model of marine bubbles.In addition,the effects of different condition parameters on link attenuation,entanglement,channel capacity,and channel BER are analyzed according to the extinction coefficient of bubbles,and simulation experiments are conducted.The results show that the increase in bubble concentration and transmission distance increases the link attenuation and BER,and the channel capacity decreases for amplitude damping channel,depolarization channel,and bit-flip channel.The channel entanglement decreases with the increasing bubble radius and decreasing depth,and the impact of marine bubbles on communication performance cannot be ignored.Meanwhile,parameters related to underwater quantum communication should be adjusted appropriately according to the concentration of marine bubbles to reduce the impact of the marine bubble environment on the communication system and improve the reliability of the communication system in practical application.