超导纳米线单光子探测器（SNSPD）对短波红外光子的探测展现出极好的性能，在高速的光通信，量子信息处理，飞行时间测距等领域具有重要的应用前景。然而，进一步提升SNSPD的性能是十分迫切的。如何在保证高探测效率的同时，实现高计数率的器件是目前研究的热点。与传统的NbN材料相比，NbTiN被认为是实现这一目标的合适材料。我们建议从NbTiN薄膜材料出发，器件设计和制备为实现手段，针对器件的本征探测效率、计数率这两个相互关联的物理量开展细致研究。具体研究内容包括：（1）薄膜组分比对超导特性的影响及其可控制备；（2）薄膜组分比对本征探测效率、计数率的影响规律；（3）在光子探测过程中电热弛豫时间的相互关系。本项目有望加深对SNSPD探测机理的认识，特别是对本征探测效率、电热弛豫时间的理解；同时为实现高效、高速SNSPD提供参考。

Superconducting nanowire single photon detector (SNSPD) exhibits high performances in detection of short-wave infrared photons. SNSPD has significant applications in high speed optical communication, quantum information processing, time-of-flight depth ranging and many other areas. However, a further improvement of SNSPD performances is quite urgent. How to simultaneously achieve a SNSPD with high detection efficiency and high count rate is still a challenge for researchers. NbTiN thin film is considered as a suitable material to satisfy such demands, in contrast to the widely used NbN. We propose to carry out detailed research on the intrinsic detection efficiency and count rate of NbTiN-based SNSPDs. We design and fabrication of NbTiN thin films and devices. Specific studies include: (1) the influence of the thin film with different compositions on their superconducting properties, and the realization of controllable preparation of thin film; (2) the influence of the film compositions on the intrinsic detection efficiency and count rate; (3) the relationship between the electro-thermal relaxation time during a photon detection event. This project may provide a further understanding on the mechanisms of SNSPD detection, especially the intrinsic detection efficiency and electro-thermal relaxation time. It could also offer useful references for high-speed and efficient SNSPDs.