Study On Quantum Light Source In Continuous Variable Quantum Illumination

With the continuous improvement of the measurement sensitivity of traditional technologies,radar detection technology will face problems such as detection sensitivity limited by quantum noise and easy to be interfered by clutter background noise in complex electromagnetic environment in the future,which poses a severe challenge to environmental situational awareness.The complex electromagnetic environment requires the radar system to have strong anti-jamming ability and anti-clutter ability,so as to improve the detection performance of radar.Traditional radar is easily affected by background noise and loss,which limits the performance of radar target detection and environmental perception.Quantum radar is a new radar detection technology that introduces quantum technology into the framework of classical radar.It uses quantum characteristics different from classical electromagnetism to improve the performance of radar.Current quantum lidar can be divided into three categories,depending on how quantum means are introduced.The first type is interferometric quantum lidar,which is based on the principle of Mach-Zehnder interferometer.The second type is the receiver quantum enhanced quantum lidar.The third type of quantum lidar is quantum illumination lidar.First proposed by Seth Lloyd in2008,quantum illumination works by sending half of the entangled beam(the signal light)to the target area for detection,while reserving the other half(the idle light)for a phase-sensitive joint measurement of the returned signal.Because there is a strong correlation between the entangled photon pairs,they can still maintain a high correlation property even under high environmental loss.Therefore,quantum illumination method can still detect the target effectively under high loss and high background noise.Two single-mode squeezed states can generate entangled light fields through phase correlation coupling.The squeezed light field is an important quantum resource in quantum optics research.One of the standard variances of the two quadrature components of the squeezed state is less than the quantum noise limit.Therefore,in the optical precision measurement,the detection sensitivity beyond the quantum noise limit can be obtained by using the quadrature component of the squeezed state light field whose noise is less than the shot noise limit.Optical parametric oscillation technique is one of the most effective methods to produce squeezed state light field with strong squeezing.Significant progress has been made in quantum illumination based on separated variable entangled light fields,but continuous variable quantum illumination radar is still in the process of further research.This paper mainly studies the quantum light source in continuous variable quantum illumination,and the main innovation points are as follows:1.The definition and types of optical resonators are introduced,and the energy transmission characteristics,transmission function and spectral characteristics of noise transmission of under-coupled,impedance matched and over-coupled optical resonators are compared and analyzed.It is proved that the optical resonator has the characteristics of power beam splitting,frequency filtering and noise conversion.It provides a foundation for the analysis and control of quantum noise,and will promote the development of precision measurement.2.The concrete structures of the degenerate single and double resonant OPO are given,and the relationship between their threshold,line width and squeezing bandwidth and the transmittance of the cavity output coupling mirror is theoretically analyzed and verified by experiments.The squeezing bandwidth is related to the linewidth of the OPO cavity,and the linewidth can be increased by increasing the transmittance of the output mirror to increase the squeezing bandwidth.In addition,increasing the transmittance of the output mirror can obtain a large escape efficiency and obtain a high squeezed light field.The advantages and disadvantages of the two types of cavity in the preparation of broadband squeezed state light field are compared.Compared with the single resonant OPO,the double resonant OPO has lower threshold value and higher locking stability,which makes it easier to prepare the broadband squeezed state field.3.The principle and advantages of quantum illumination are briefly described,and the detection scheme of continuous variable quantum illumination is proposed.The squeezed state light field is applied to the experimental research of quantum illumination.