Tailoring Superconducting Nanowire Single-Photon Detectors for Quantum Technologies

Superconducting nanowire single-photon detectors (SNSPDs) are a key building block for photonic quantum technologies, as they provide a means for efficient readout of optical circuits with low timing jitter, dark counts and dead time. In this contribution we give a general overview of the working principle of these devices and look into several engineering aspects. We discuss the influence of the stoichiometry of NbTiN thin-films on detector performance and find that a ratio of 65:35 Nb:Ti results in the highest saturation of SNSPDs fabricated from these films. Furthermore, we study the impact of helium ion irradiation on the efficiency of SNSPDs. We show that with this technique the efficiency of an SNSPD can be improved from below 1% to 42%. Finally, we discuss the impact of embedding the SNSPDs into an optical cavity on the system detection efficiency. By employing a half-cavity under the detector we are able to boost the efficiency from 30% to 50% for a detector with a fill factor of 0.33.