| Quantum radar can achieve super-resolution,super sensitivity and many other advantages over traditional radar by using quantum signal and optical quantum measurement technology.So far,three types of quantum radar have been developed by domestic and foreign research teams:interference quantum radar,receiver quantum enhanced radar and quantum illumination radar.Among them,the quantum radar with interference scheme has unique advantages.Radar is widely used in military,national defense,scientific research,people's livelihood and other fields.After half a century of development,its mission is more and more important.However,at the same time,the traditional radar also faces many severe challenges brought by the rapid development of electronic jamming,stealth technology,etc.;due to the classical electromagnetic theory,the traditional radar technology is difficult to break through the technical bottleneck in improving resolution,sensitivity,anti-jamming ability,etc.Therefore,the existing radar technology is in urgent need of further improvement in detection performance and anti-jamming ability,so as to meet the increasingly demanding application requirements.Since the birth of quantum information technology,its potential value and wide application prospects have attracted the attention of all walks of life.In theory,it has brought us many new methods and new ideas to break through the classical information processing.Quantum radar,based on quantum theory,introduces quantum optics and quantum information technology into the field of radar detection.By using quantum state signal and optical quantum measurement technology,we can realize the super-resolution,super sensitivity and many other performances of quantum radar,which has incomparable advantages over traditional radar.At present,three different types of quantum radar have been developed:the quantum Interferometric Radar,the quantum enhanced radar at the receiving end and the quantum illumination.Among them,the quantum radar with the interference scheme has incomparable advantages over other schemes.Based on this background,quantum interference radar is studied in this paper.The detection of targets in the atmosphere by quantum radar is influenced by the atmosphere medium.The absorption and scattering of photons by atmospheric molecules and aerosol particles lead to signal attenuation.Atmospheric turbulence makes photons drift,expand,flicker,phase fluctuation and other effects in the process of propagation.These turbulence effects make quantum light field lose its quantum characteristics gradually,which seriously affects the resolution,sensitivity and other performance of quantum radar.It is the basis of the practical application of quantum radar to build the atmospheric propagation model of quantum light field and study the mechanism of the influence of atmospheric medium on quantum radar.Although the theory of atmospheric propagation of light wave as electromagnetic wave has been mature,the research of atmospheric propagation of quantum light field has not been carried out systematically,so it is necessary to carry out systematic and in-depth theoretical research on the mechanism of atmospheric influence of quantum radar.In this paper,the quantum interference radar based on coherent state light source is chosen as the research object,and the mechanism of the influence of the quantum radar on the atmosphere is studied.The main research work and innovative achievements are as follows:1)The basic principle of interferometric quantum radar technology is analyzed.In this paper,Mach Zehnder interferometer is used as the model of quantum interference radar,and the method and results of the classical theory of light wave propagation in the atmosphere are used for reference.At the same time,we explore the research methods of optical quantum propagation in the atmosphere,establish the preliminary research ideas and framework,and expand the influence of the atmosphere on the quantum light field to the field of quantum optics through the master equation.2)The interference quantum radar based on coherent state light source is calculated in detail.According to the basic structure and principle of Maher zenDel interferometer,this paper mainly deduces the echo signal transmitted by the quantum interference radar through the atmosphere with the coherent state as the light source,gives the specific analytical expression,and selects the corresponding detection scheme,proving that the quantum interference radar has super resolution and super sensitivity characteristics beyond the diffraction limit.3)Combined with the classical atmospheric light propagation theory,a set of atmospheric transmission model of quantum light field is derived.In this paper,the classical atmospheric transmission theory and quantum optics are combined,and the electric field propagation is given by the classical theory.According to the results,a quantum operator is constructed to describe the evolution of the quantum light field in the atmospheric medium.In essence,this theory belongs to semi classical/semi quantum theory.Although it has some limitations and has not been verified by experiments,as a pioneering work,it lays a foundation for the follow-up research in this field;4)The atmospheric influence mechanism of interference quantum radar based on coherent state light source is studied.In this paper,the effects of atmospheric attenuation,atmospheric scintillation and atmospheric phase fluctuation on the quantum interference radar are analyzed,and the probability density function of atmospheric transmittance about atmospheric scintillation is derived.It is found that the atmospheric attenuation and scintillation effect are beneficial to the quantum interference radar to a certain extent,and the influence of the atmosphere on the detection performance can be reduced to a certain extent by properly adjusting the parameters of the quantum radar,such as the receiving aperture,the average photon number and the phase diffusion rate of the receiving end.For example,when the transmission power is increased,the sensitivity of the system may be reduced.In this paper,a set of atmospheric transmission model of quantum light field is derived,and the theoretical model of quantum interference radar and its signal detection scheme based on coherent state light source is constructed.It is proved that quantum interference radar has super-resolution characteristics beyond diffraction limit.After further supplement and improvement,the model can be applied to the design and development of practical quantum radar. |
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