Research On Timing Jitter Of Superconducting Nanowire Single-photon Detectors

Since invented in 2001,superconducting nanowire single-photon detectors(SNSPDs)have attracted significant amount of research interest due to their high detection efficiency,low dark-count rate,low timing jitter and high counting rate.Although the performances of SNSPDs have been quite decent,these decent characteristics of performances have not been simultaneously realized in one device.In particular,tradeoffs exist between detection efficiency and timing jitter.To realize SNSPDs with both high detection efficiency and low timing jitter,we first need to theoretically clarify the mechanisms of the timing jitter in order to provide basis for experimentally decreasing the timing jitter;we also need to innovate the device structures to decrease the timing jitter without affecting the detection efficiency.This thesis focuses on these two aspects – the mechanism of timing jitter of SNSPDs and the device structure to decrease the timing jitter without affecting the detection efficiency.In the theoretical aspect of timing jitter,this thesis clarifies one mechanism of timing jitter of the SNSPDs – the spatial-inhomogeneity-induced timing jitter.This thesis establishes a model for modeling and analyzing this type of timing jitter and discuss the methods to measure and reduce it.In the aspect of device structures for decreasing the timing jitter,this thesis proposes SNSPDs integrated with current reservoirs,which reduces the noise-induced and inhomogeneity-induced timing jitter without affecting detection efficiency.This thesis presents the concept and the working principle and the design,fabrication,and testing of the devices.The major performances predicted by our theories have been confirmed experimentally,including amplifying the output pulses,increasing the signal-to-noise ratio,decreasing the timing jitter without affecting the detection efficiency.Both the theoretical and experimental results lead us to conclude that SNSPDs integrated with current reservoirs can simultaneously realize high detection efficiency and low timing jitter.