Research On Quantum Microwave Magnetic Field Detection And Imaging System And Its Application

There is a kind of defect formed by Nitrogen-Vacancy in natural diamonds.The defect capturing a free electron is called(1~-center.Because the diamond with this defects shows red color,the(1~-center is also called NV color center.NV color center present excellent optical properties,and is an ideal single photon source.It has good electron spin characteristics at room temperature.Therefore,NV color center is widely used in quantum metrology,quantum information processing(QIP)and quantum magnetic field measurement and imaging.This paper mainly studies the quantum microwave magnetic field detection and imaging system based on diamond NV color center,explores the vector microwave field reconstruction and imaging method based on magneto-optic effect,and studies the application of the system in the field of electromagnetic compatibility.Based on the excellent quantum optical properties of diamond NV color centers,this paper focuses on the research of quantum microwave field imaging system from three aspects:improving the detection efficiency of the system,enhancing the detection sensitivity of the system,expanding the detection frequency of the system.The main research contents are as follows:1.In terms of improving the detection efficiency of the system,a fast microwave field imaging method with wide field of view based on CCD camera and(1~-rich diamond film is explored.The method of fast microwave field imaging based on Kohler illumination is studied,and a multi-channel pulse generator is used to synchronize CCD camera,laser switch,microwave switch and microwave source.The difference measurement method between reference frame and image frame is used to reduce the measurement noise;n repetitive sequences are integrated in each frame to further improve the signal to noise ratio(SNR).In this paper,a software scanning microwave imaging method is developed.Through point-by-point software analysis of the image of CCD camera,the optical detection magnetic resonance(ODMR)spectrum or Rabi oscillation(Rabi)curve of each pixel is drawn.Then the intensity of the microwave magnetic field corresponding to each pixel is obtained by data fitting,and then the amplitude and phase signals information are calculated by the full vector microwave field reconstruction formula.The full vector microwave field reconstruction formula is derived from the measured left and right circularly polarized microwave magnetic field components on four NV axes.This paper verifies the correctness of the whole experimental system by measuring a micro helical antenna.2.In order to improve the detection sensitivity of the system,a highly sensitive quantum measurement method of diamond NV color center microwave field based on amplitude and frequency modulation technology is studied in this paper.A microwave magnetic field detection method and experimental system based on AM-FM optical detection magnetic resonance technology are developed,and the corresponding surface current reconstruction algorithm is proposed.A special diamond microwave probe is fabricated and placed on the surface of microwave device or antenna to detect microwave field.The probe is made by attaching diamond particles to the top of the fiber without disturbing the microwave field.The system has a very narrow bandwidth filter to filter out most of the noise,and this method has better detection sensitivity.Although this method uses scanning method to realize the measurement and imaging of microwave field,this method greatly reduces the measurement time of each scanning point and can reach millisecond level.The three-dimensional vector magnetic field information can be measured by using the NV color centers of different orientations in the diamond probe.The current distribution on the antenna surface can be reconstructed more accurately by using three-dimensional vector magnetic field information.By measuring a patch antenna,the correctness of the experimental system is verified.3.In order to expand the detection frequency of the system,a high resolution,noninvasive broadband microwave field imaging method is explored in this paper.Such method is realized by using a diamond sensor with rich NV color centers under static bias magnetic field.The detection sensitivity of the system can reach 15 MHz.The spatial resolution is limited by the size of the diamond probe and the accuracy of the displacement platform,which can reach the micron level.This technology is based on the fact that the external AC magnetic field can adjust the fluorescence intensity of the diamond NV color center under 532 nm green laser pumping and biased by the off-axis static magnetic field.The minimum detection sensitivity of this system can reach 0.1 Gauss,and is mainly limited by the background noise of APD.In this paper,a circular planar helical antenna is measured to verify the correctness of the experimental system.The near-field imaging of a Ga As substrate MMIC low-pass filter chip is also carried out by using the quantum magnetic field imaging system,and the EMC problems presented by the chip imaging are analyzed.Finally,the research of the microwave field imaging system is summarized,and the future research of the microwave field imaging system are prospected.