Fabrication And Parameter Calibration Of Josephson Junction For Microwave Single Photon Detection

Quantum information technology represented by quantum communication and quantum computing is a hot research topic in the world today.High performance,all band single photon detector is the core device of quantum information technology.With the development of quantum information technology,Semiconductor single photon detector has been unable to meet the requirements.The appearance of superconducting edge transition detector,superconducting nanowire single photon detector and microwave dynamic inductor single photon detector has greatly improved the detecting ability of single photon detector in infrared to X-ray band.To a great extent,the detection performance of the single photon detector in the infrared to X-ray band is improved.However,there are no mature single-photon detectors in the microwave band.At present,Josephson junction with current bias has been applied to microwave single photon detection and some research results have been obtained.In addition,Josephson junction as a basic component of quantum bit has more extensive applications in the field of quantum computing.The research on the fabrication process of Josephson junction is the basis of its application in single-photon detection and quantum computing.In this paper,based on the existing ultraviolet exposure machine and electron beam evaporation coating instrument in the laboratory,after adjusting and refitting the experimental equipment,using the floating mask and the oblique angle evaporation coating process,the Josephson junction sample was successfully prepared.The junction area of the designed Josephson junction is 4?m~2.Al is used as the superconductor at both ends,and Al O_x is used as the barrier layer,that is,the Al-Al O_x-Al three-layer structure.The I-V characteristic curve and statistical distribution data of the jump current of the prepared Josephson junction sample were obtained under the 50m K extremely low temperature environment with the designed measurement circuit.This laid the foundation for its application in quantum computing and single-photon detection in the next step.As the core device for realizing superconducting quantum computing and microwave single-photon detection,the Josephson junction is difficult to directly measure its physical parameters.In previous studies,whether it is based on the hysteresis current in the I-V characteristic curve to calibrate the damping parameters,or based on the measurement of the high-frequency microwave excitation response under microwave drive,each has its limitations.In this paper,the Josephson junction I-V curve and the statistical distribution of jump current driven by low frequency current are measured experimentally.The critical current,capacitance,resistance,damping,and other physical parameters of Josephson junction are calculated by comparing the experimental data with the numerical simulation of standard RCSJ model.And other physical parameters.The results show that the calculated parameter values are basically consistent with the damping parameter values calibrated based on the I-V characteristic curve.This method can be used as a reference for the on-demand design of the device parameters of the Josephson junction and the parameter settings of the fabrication process.