High resolution, high signal-to-noise ratio and high sensitivity have always been the goals and technical bottlenecks of detection, precision measurement and imaging. Quantum detection technology is one of the disruptive cutting-edge technologies in the world. Quantum information technology is introduced into the field of classical detection, hoping to solve the difficult technical bottleneck on the basis of classical physics. Compared with traditional detection methods, quantum detection has higher sensitivity, can receive weaker signals, requires lower transmission power, and has stronger anti-interference ability. In terms of precision measurement, the characteristics of quantum mechanics are used to make the measurement accuracy break through the classical physical limit, and then improve the measurement accuracy of the detection system. But with the development of remote sensing technology and people demand for long distance detection, we completed in the early completed close quantum detection, combined with remote sensing technology, the quantum squeezed light into the receiving system, using quantum phase-free amplification technology, make up for the low efficiency of the detector, make its imaging results close to the ideal detector. We designed a set of quantum squeezing light preparation, emission /receiving system, quantum enhancement module, quantum imaging system, balance homodyne detection system, data processing system, central control system in one of the remote quantum infrared detector, effective detection distance up to 100 meters, at the same time achieve high resolution imaging, the same environment and classical laser imaging resolution increased by 1 to2 times. In March 2000, Professor Siwen Bi conducted the exploration and research on quantum remote sensing. At the beginning of 2001, Professor Siwen Bi first put forward the concept of quantum remote sensing at home and abroad. In the past 20 years, through three stages of basic theoretical scientific experiments and key technologies, we have overcome many difficulties in theoretical research scientific experiments and key technologies ,and achieved breakthrough progress and innovative results, which have laid a key foundation for the follow-up quantum laser radar quantum remote sensing products.
High resolution, high signal-to-noise ratio and high sensitivity have always been the goals and technical bottlenecks of detection, precision measurement and imaging. Quantum detection technology is one of the disruptive cutting-edge technologies in the world. Quantum information technology is introduced into the field of classical detection, hoping to solve the difficult technical bottleneck on the basis of classical physics. Compared with traditional detection methods, quantum detection has higher sensitivity, can receive weaker signals, requires lower transmission power, and has stronger anti-interference ability. In terms of precision measurement, the characteristics of quantum mechanics are used to make the measurement accuracy break through the classical physical limit, and then improve the measurement accuracy of the detection system. But with the development of remote sensing technology and people demand for long distance detection, we completed in the early completed close quantum detection, combined with remote sensing technology, the quantum squeezed light into the receiving system, using quantum phase-free amplification technology, make up for the low efficiency of the detector, make its imaging results close to the ideal detector. We designed a set of quantum squeezing light preparation, emission /receiving system, quantum enhancement module, quantum imaging system, balance homodyne detection system, data processing system, central control system in one of the remote quantum infrared detector, effective detection distance up to 100 meters, at the same time achieve high resolution imaging, the same environment and classical laser imaging resolution increased by 1 to2 times. In March 2000, Professor Siwen Bi conducted the exploration and research on quantum remote sensing. At the beginning of 2001, Professor Siwen Bi first put forward the concept of quantum remote sensing at home and abroad. In the past 20 years, through three stages of basic theoretical scientific experiments and key technologies, we have overcome many difficulties in theoretical research scientific experiments and key technologies ,and achieved breakthrough progress and innovative results, which have laid a key foundation for the follow-up quantum laser radar quantum remote sensing products.
Based on the development and application needs, Professor Siwen Bi has proposed quantum remote sensing (QRS) in the early 2001. Firstly, the paper introduces the background, concept and research status at home and abroad of quantum remote sensing, it also introduces the differences and advantages of quantum remote sensing compared with the classical remote sensing. Then it elaborates wave-particle duality, Superposition State, Tunneling Effect of QRS research basis and quantum entanglement, its basic theory and information mechanism, as well as the research progress of QRS imaging processing, quantum spectrum remote sensing and QRS calibration. Besides, it emphasizes the experimental process of QRS imaging and the production of principle prototype, based on which, Professor Bi proposed active imaging information transmission technology of satellite borne QRS technical solutions and conducted research on its system composition and working principle, squeezing light preparation of active imaging, injection device and quantum non-noise amplifier device, providing solutions and technical basis for realizing active imaging technology of satellite-borne QRS. The QRS imaging technology can significantly improve the signal-to-noise ratio and space resolution of QRS imaging information transmission. Finally, the paper summarizes the research conditions over the past eighteen years and plan for the future.
Based on the basic theory, information mechanism and imaging experiment of quantum remote sensing, quantum spectral imaging and quantum detection and identification, as well as the production of principle prototype, the author conducted researches on high-sensitivity target detection of infrared optical quantum squeezing that can breakthrough quantum noise limit, high resolution imaging technical solutions and imaging principle experiment, focusing on realizing of high sensitivity long-range target detection, system composition and working principle of high-resolution imaging experimental device, infrared quantum optical squeezed light preparation and injection, and quantum noiseless amplifier, aiming to resolve relevant crucial problems, which provide technical basis for the production of engineering prototype and its experimental device. Besides, based on the project assignment, the paper firstly introduces research status at home and abroad, the development tendency, and research significance and necessity, then it emphasizes the research target, research content and key technical index, as well as the overall technical solutions, solutions and feasibility analysis for key technologies. Finally, it summarizes benefit analysis, project arrangement and outcome forms.
According to the development and application needs of Remote Sensing Science and technology, Prof. Siwen Bi proposed quantum remote sensing. Firstly, the paper gives a brief introduction of the background of quantum remote sensing, the research status and related researches at home and abroad on the theory, information mechanism and imaging experiments of quantum remote sensing and the production of principle prototype.Then, the quantization of pure remote sensing radiation field, the state function and squeezing effect of quantum remote sensing radiation field are emphasized. It also describes the squeezing optical operator of quantum light field in active imaging information transmission experiment and imaging experiments, achieving 2-3 times higher resolution than that of coherent light detection imaging and completing the production of quantum remote sensing imaging prototype. The application of quantum remote sensing technology can significantly improve both the signal-to-noise ratio of information transmission imaging and the spatial resolution of quantum remote sensing .On the above basis, Prof.Bi proposed the technical solution of active imaging information transmission technology of satellite borne quantum remote sensing, launched researches on its system composition and operation principle and on quantum noiseless amplifying devices, providing solutions and technical basis for implementing active imaging information technology of satellite borne Quantum Remote Sensing.
In classical physics, the detection of any physical quantity is accompanied by noise, including the classical noise of the system and quantum noise, which limits the detection accuracy. Among them, the classical noise mainly comes from technical defects, the advantages and disadvantages of instruments and other factors. With the development of science and technology, the classical noise of the system is greatly reduced and can often be ignored. Therefore, quantum noise determined by quantum mechanical properties gradually becomes the main source of noise. The squeezed light source has the quantum property that a certain orthogonal component can be lower than the shot noise limit, which breaks through the standard quantum noise limit and further improves the detection accuracy. As a kind of non-classical light, the squeezed state has great application potential in the field of quantum optics. Based on the stable working squeezed light prepared in the early stage, and combining with the theory, experiment and key technology of Professor Bi over 20 years, we have developed a set of instrumentized short-range quantum infrared detector. Special design is made in light source, detection system, pattern matching, phase locking, structure design and packaging, which can effectively improve detection accuracy and imaging quality in the range of 0.5m-9m, and then used in light source correction such as transverse displacement and tilt measurement of light beam and various detection under special conditions such as weak light.
As a combination of laser technology and modern photoelectric detection technology, lidar (laser radar) has notable advantages compared with traditional radar such as high resolution, strong anti-interference ability, and good low-altitude detection performance. However, with continuous application in aerospace, military, artificial intelligence and other fields, lidar has reached the limits of classical physics and can’t meet the requirements in detection, measurement and imaging. In order to break the bottleneck, worldwide researchers have developed a new type of radar-quantum lidar, which is based on the combination of traditional radar technology and quantum information technology. Its main principle is to get imaging through squeezed light that is below the noise limit of classical physics and then manipulated by the quantum state to achieve imaging with higher quality. Quantum lidar in the paper injects quantum squeezed light to receiver end and uses quantum phase-sensitive amplifier technology to compensate the photon loss that caused by insufficient quantum power to further improve resolution. In the squeezed light, the generation of quantum squeezed light and detection theory are studied, the resonant cavity locking principle and balanced homodyne detection principle are analyzed, and a mode cleaner with narrow line width is designed to improve beam transverse mode quality of laser and filter high frequency noise. In order to reduce quantum noise and improve resolution, quantum lidar imaging system is developed and the theoretically derivation and numerical simulation results show that the resolution of quantum lidar imaging is 1.71 times higher than that of lidar imaging.
Lidar (laser radar) offers advantages over conventional radar in terms of higher resolution, greater anti-interference capability and ultra-low altitude detection performance. However, Lidar has now reached a bottleneck in terms of detection range and is no longer able to correctly identify targets beyond 500 meters, thus failing to meet the requirements for detection, measurement and imaging. To break this bottleneck, we have developed a Quantum Lidar with a detection range of up to one kilometre, which is based on a quantum vacuum squeezed laser and can compress the photon fluctuation by 5.6dB in the vacuum state through quasi-phase matching in non-linear crystals, reducing the quantum noise of laser which accounts for 73% of the lidar, thus reducing the overall noise of the quantum lidar by 3.27dB and improves the phase stability of the laser (from 10 minutes to more than 120 minutes) to achieve higher accuracy measurements, with a Signal-Noise Ratio (SNR) twice that of conventional lidar, and therefore a sensitivity twice as high. The basic technical implementation is to use a 20W power 1064nm wavelength continuous wave laser (CW, M2 less than or equal to 1.05) to irradiate a target located one kilometre away. By detecting a very weak reflected laser (power=10μW ± 5μW) which is exponentially attenuated by distance, We use noiseless amplification by a quantum vacuum-squeezed laser with the same power magnitude to obtain a higher power (7dB amplification) and higher signal-noise ratio (4.77dB SNR improvement). A reflective lens set (250mm aperture) of our design is used to receive the laser diffusion due to the 4mrad transmission angle of one kilometre. In the squeezed laser system, the resonant cavity locking efficiency is improved to 99.7%, and the re-locking time is less than 0.3s, it is directly switchable with the balance homodyne detection system. The mode cleaner improves the transverse mode quality(the mode bandwidth is reduced by 67%) while filtering high-frequency noise. The quantum lidar imaging system has been developed, and the experimental results show that the resolution of the laboratory-simulated long-range decay experiment is 3 times higher than that of traditional lidar is a promising development. This means that the system can detect and image smaller objects and features with greater accuracy and precision. The use of a self-developed quantum enhancement algorithm to obtain a 5 times higher contrast lidar image is also a significant improvement, and the use of a quantum denoising algorithm to reduce graphic distortion and image scatter caused by atmospheric pollution and environmental interference is a critical development. These issues can significantly degrade the quality of lidar images, so being able to mitigate their effects is a significant step forward. Through a self-developed LiDAR 3D reconstruction algorithm, the reconstruction efficiency is increased by 3 times and the resolution is increased by 2.5 times, which means that the reconstructed 3D model is faster, more detailed and accurate. In the future, based on one kilometre's work, achieving a quantum lidar with a detection distance of 10, 20 or even 50 kilometres with much clearer images would require advancements by steadily improving the resolution, improving the signal-noise ratio of the system, improving the laser power and optimising the algorithm.