To study the influence of black carbon aerosols on the detection performance of quantum interference radar, the extinction characteristics of black carbon aerosol particles are analysed by using lognormal distribution, combined with Mie scattering theory, and the relationship between the concentration of black carbon aerosol particles and the extinction coefficient is established; the mathematical model of the influence of black carbon aerosol particles on the transmission distance, radar resolution and channel fidelity of quantum interference radar detection photons are also established and simulated. The simulation results show that with the increase of black carbon aerosol particle concentration, the extinction coefficient increases linearly, the link attenuation factor increases, and the transmission distance of the detection light quantum signal decreases; when the number of pulse photons emitted by the quantum interference radar is certain, the resolution of the quantum interference radar decreases with the increase of the optical thickness of black carbon aerosol particles; when the transmission distance of the detection light quantum signal is certain, the quantum interference radar channel The fidelity decreases as the concentration of black carbon aerosol particles increases, but, the minimum value of fidelity is not less than 0.9. Therefore, in the design and use of quantum interference radar, each index parameter of the quantum interference radar system should be adjusted adaptively according to the relevant parameters of black carbon aerosol particles to improve the detection performance of quantum interference radar.
To study the influence of black carbon aerosols on the detection performance of quantum interference radar, the extinction characteristics of black carbon aerosol particles are analysed by using lognormal distribution, combined with Mie scattering theory, and the relationship between the concentration of black carbon aerosol particles and the extinction coefficient is established; the mathematical model of the influence of black carbon aerosol particles on the transmission distance, radar resolution and channel fidelity of quantum interference radar detection photons are also established and simulated. The simulation results show that with the increase of black carbon aerosol particle concentration, the extinction coefficient increases linearly, the link attenuation factor increases, and the transmission distance of the detection light quantum signal decreases; when the number of pulse photons emitted by the quantum interference radar is certain, the resolution of the quantum interference radar decreases with the increase of the optical thickness of black carbon aerosol particles; when the transmission distance of the detection light quantum signal is certain, the quantum interference radar channel The fidelity decreases as the concentration of black carbon aerosol particles increases, but, the minimum value of fidelity is not less than 0.9. Therefore, in the design and use of quantum interference radar, each index parameter of the quantum interference radar system should be adjusted adaptively according to the relevant parameters of black carbon aerosol particles to improve the detection performance of quantum interference radar.
In order to study the influence of PM2.5 particles on the detection performance of quantum interference radar, this article analyzes the relationship between the concentration of PM2.5 particles and the extinction coefficient under different particle sizes based on the spectral distribution function of PM2.5 particles and the Mie scattering theory. Then establish the influence model of PM2.5 particles on the detection distance and maximum detection error probability of quantum interference radar. The simulation results show that as the concentration of PM2.5 particles increases, the extinction coefficient of PM2.5 particles shows a gradually increasing trend; the energy of the detected photons is attenuated, resulting in a decrease in the transmission distance of the photons; when the energy of the emitted photons remains unchanged, The maximum detection error probability of quantum interference radar increases with the increase of PM2.5 particle concentration; when the PM2.5 particle concentration remains unchanged, the maximum detection error probability decreases gradually with the increase of the emitted photon energy. Therefore, the average number of emitted photons should be appropriately adjusted according to PM2.5 pollution in order to reduce the impact of PM2.5 atmospheric pollution on the detection performance of quantum interference radar.
Abstract Soot aerosol is an important part of atmospheric aerosol, which has important influence on the propagation of quantum signal. In order to study the influence of soot aerosol on satellite-ground quantum communication, according to the size distribution parameter and extinction coefficient of the soot aerosol, the influence of the concentration of the soot aerosol particles and the transmission distance on the attenuation of the link is analyzed. The simulation experiments of channel capacity, channel fidelity and channel bit error rate (Ber) are carried out with amplitude-damped channel. The simulation results show that the soot aerosol concentration increases from 2.1×10 6 / m 3 to 3.2 10× 6 / m 3 , the link attenuation factor increases from 0.3dB/ km to 0.46dB/ km, the fidelity decreases from 0.98 to 0.97, and the bit error rate increases from 0.0087 to 0.0122 at a transmission distance of 3km . hhen the transmission distance is 6km and the particle concentration is 2.1×10 6 / m 3 , 2.7 10× 6 / m 3 and 3.9×10 6 / m 3 , the channel capacity increases from 1.078 to 1.0809, and then decreases to 1.0804. Therefore, the soot aerosol has influence on the performance of satellite-ground quantum communication, and the degree of influence is different. In order to ensure the reliability of quantum communication between satellite and ground, the parameters can be adjusted to ensure the normal transmission of quantum signal.
In quantum satellite communication, when the optical quantum signal is transmitted between satellite and ground links, it will be affected by various natural environments.At the same time, haze has become one of the largest environmental problems in the world.Therefore, it is of great significance to study the communication performance of quantum satellites in haze atmosphere.In this paper, according to the scale distribution and vertical spatial concentration change of large aerosol haze particles, the extinction characteristic model of large aerosol haze particles and the attenuation model of atmospheric haze particle concentration and transmission height on quantum satellite ground link are established.Some important performance parameters in quantum satellite communication are analyzed for amplitude damping channel, depolarization channel and phase damping channel respectively, It includes the quantitative relationship between channel capacity, quantum fidelity, quantum bit error rate and entanglement and large aerosol haze particle concentration and transmission height.The simulation results show that with the increase of transmission distance and haze particle concentration, the channel capacity, quantum fidelity and entanglement of quantum satellite communication in different channels will decrease, and the bit error rate will increase.Therefore, the impact of large haze environment on quantum satellite communication should be fully considered in the actual process of quantum satellite communication, Adaptive adjustment of relevant parameters to ensure the normal operation of quantum satellite communication.
This work is to study the effects of charged sand/dust atmosphere on the performances of microwave quantum illumination (QI) radar. Based on Mie particle scattering theory, using a Monte Carlo method for simulating the physical process in which photon is scattered multiple times by discrete random distributed particles, the specific attenuation (dB/km) of microwave propagating in sand/dust atmosphere are analyzed under the conditions of varying atmospheric visibility and sand/dust particles with different charged quantities. It is indicated that the specific attenuation obtained by multiple scattering is smaller than that obtained based on Mie theory, for microwave propagating in charged sand/dust atmosphere. The smaller the atmospheric visibility, the greater the difference is, while the difference decreases gradually as the atmospheric visibility increases. Then, it is more reasonable to consider multiple scattering attenuation at lower atmospheric visibility. When sand/dust particle is charged, the specific attenuation is increased, however, this increase is not linear. According to quantum illumination radar theory, a beam splitter-based optical link model is used to simulate the sand/dust atmospheric channel. The effects of charged sand/dust atmosphere with different visibility on the detection error probability, signal-to-noise ratio, and maximum detection range for microwave quantum illumination radar are studied by using quantum radar equation and quantum detection error probability theory. The performances between QI radar and classical two-mode noise (TMN) radar are compared and analyzed. These results show that the performances of quantum illumination radar are improved with sand/dust atmospheric visibility increasing. When sand/dust particles are charged, the performances for QI radar are degraded due to attenuation increasing. The change in the performance is nonlinear with the variation of sand/dust carrying charge quantity. When visibility is high, increasing the signal frequency can improve the performance of quantum illumination radar, but when visibility is low, the gain of frequency increase is offset by the performance decline caused by attenuation increase. Therefore, it is not recommended to increase the frequency in such a case. The comparison with classical radar reveals that QI radar performs better under the condition of lower atmospheric visibility and lower average photon emission, but this advantage diminishes as the number of photons increases. In a word, these results show that the performances of QI radar are more significant at lower atmospheric visibility. Under higher visibility conditions, the QI system SNR can be improved by increasing frequency. The maximum detection range of the QI radar is significantly better than that of the classical TMN radar.
Quantum satellite communication is a communication method with strong security and large coverage area, and it has become a hot research topic at home and abroad. The successful launch of the quantum satellite has laid an important foundation for future integrated quantum communication. When further studying the communication performance between quantum satellite-ground links, it is found that atmospheric particulate matter has a significant impact on quantum satellite communication performance. In this paper, by analyzing the extinction characteristics of atmospheric particles, a mathematical model of particle concentration, transmission distance and satellite-earth quantum energy is established, and the influence of atmospheric particles on communication parameters, bit error rate and entanglement degree is analyzed. The simulation results show that with the increase of particle concentration, the performance indicators of quantum satellite communication are affected to a certain extent. As the concentration of particulate matter in the atmosphere continues to decrease, the energy of the optical quantum signal continues to increase, and the quantum bit error rate increases with the increase in the concentration of atmospheric particulate matter and the transmission distance. The degree of quantum entanglement decreases with the increase of the particle size of atmospheric particles, and increases with the increase of visibility. The luminosity of light quantum will decrease with the increase of transmission height and the increase of surface particle concentration. By studying the optimization and adjustment strategy of quantum signal based on fidelity quantum relay satellite, simulation ensures the feasibility of this strategy. It is observed that the research in this paper can provide the necessary theoretical reference for the development of quantum space-ground integrated communication network.
There has been aroused much interest in quantum metrology such as quantum radar, due to its applications in sub-Raleigh ranging and remote sensing. For quantum radar, the atmospheric absorption and diffraction rapidly degrade any actively transmitted quantum states of light, such as N00N and MM' states. Thus for the high-loss condition, the optimal strategy is to transmit coherent state of light, which can only provide sensitivity at the shot-noise limit but suffer no worse loss than the linear Beer's law for classical radar attenuation. In this paper, the target detection theory of quantum interferometric radar in the presence of photon loss is thoroughly investigated with the model of Mach-Zehnder interferometer, and the dynamic evolution of the quantum light field in the detecting process is also investigated. We utilize the parity operator to detect the return signal of quantum interferometric radar with coherent-state source. Then we compare the detection result of quantum radar with that of classical radar, which proves that the quantum radar scheme that employs coherent radiation sources and parity operator detection can provide an N-fold super-resolution, which is much below the Rayleigh diffraction limit; besides, the sensitivity of this scheme can also achieve the shot-noise-limit. Also, we analyze the effect of atmospheric attenuation on the performance of quantum radar, and find that the sensitivity is seriously influenced by atmospheric attenuation:only when the reference beam and the detection beam have the same transmissivity, will the sensitivity increase monotonically with increasing the photon number per pulse N, otherwise it first increases and then decreases with increasing N. Further, the sensivity is directly proportional to 1/N for the first case. In conclusion, we investigate the effects of atmospheric absorption on the resolution and sensitivity of quantum radar, and find that one can overcome the harmful effects of atmospheric attenuation by adjusting the transmissivity of reference beam to the atmospheric transmittance.