High comprehensive performance superconducting nanowire single photon detector

Abstract

Superconducting nanowire single photon detector (SNSPD) has been widely used in quantum communication, quantum computing and other fields because of its excellent timing jitter and response speed. However, due to the mutual restraint of the technical parameters of SNSPD nanowires, there are technical challenges to further improve the comprehensive performance of SNSPD, and thus limiting its application on a large scale. Combining high detection efficiency with high timing performance is still an outstanding challenge. In this work, we report the SNSPD with 12-μm small active area, which has high speed, high efficiency, low jitter and broadband absorption. Au/SiO<sub>2</sub> membrane cavity, which is determined by finite element analysis simulation, is used to widen the optical response bandwidth. And it is easier to process and improve the alignment accuracy at the same time. The flat substrate is more conducive to the growth of superconducting thin films, so flattening process is introduced. Device package is also optimized to match smaller detector. Self-aligned packaging makes optical alignment more convenient and time-saving. Special optical fibers with small mode-field diameters can reduce the negative effect of the detector on optical coupling. The detector can achieve a maximum SDE of 82% at the central wavelength of 1310 nm and the temperature of 2.2 K, and the SDE of more than 65% in the wavelength range of 1200–1600 nm, with DCR of 70 cps. The detector also exhibits a count rate of 40 MHz@3 dB and a timing jitter of 38 ps, which is significantly improved compared with 23-μm active area detector. Furthermore, the minimum timing jitter of 22 ps can be obtained by using cryogenic amplifier readout. In this work, high comprehensive performance detector is developed, which provides an important technical reference for practical and product SNSPD.