Photon Response And Signal Processing Of Superconducting Kinetic Inductance Detector

Single-photon detection technology is the basic prerequisite for realizing optical quantum information processing.Superconducting kinetic inductance is the singlephoton detection device that can achieve high efficiency and high resolution in a lowtemperature environment.Superconducting kinetic inductance detector,also called microwave kinetic inductance detector(MKID),is a detector with great potential in millimeter and sub-millimeter waveband detection.It has the excellent characteristics that are different from traditional room temperature single-photon detectors: extremely high quality factor,high photon number resolution capability,high energy resolution,and easy to achieve large-scale integration.Its detection principle is that when photons hit the superconductor,the inner Cooper pair is broken up then become quasi particles.The change of the Cooper pair and density of quasi particles causes a change in the impedance of the microwave kinetic inductance superconductor surface,which can be read by the monitoring system.In order to processing the weak light signal response of MKID in extremely low temperature environment,this paper first discusses and compares its advantages and disadvantages with other mainstream superconducting single photon detectors,such as superconducting nanowire single photon detector and superconducting transition edge sensor.Secondly,by virtue of its simple structure,easy integration and high photon number resolution ability,In quantum communication,according to the decoy state mechanism,we explain how MKID deals with the eavesdropping behavior.Then,we introduce the photonic response process of a single photon detector with MKID in combination with IQ mixing mechanism.Next,the step of post-processing of the light response signal using the optimal filtering algorithm is explained in detail.In view of the mismatch between the optimal filtering algorithm and colored noise,we use the white noise and whitened noise to optimize the noise model of the system.By changing the noise model,the energy resolution and photon number resolution(the main performance index of single photon detector)of the detector are improved by using the optimal filtering algorithm.Finally,in combination with the photon-number distinguishing characteristic of MKID,we use pulse data which own high photon resolution ability as a template library to complete the detection of photon number of unknown single pulse.And we explore the method of accurate calibration of photon number.