Effects of helium-ion exposure on superconducting nanowires single photon detectors

Ultra-fast single-photon detectors can be useful for a lot of different applications, including quantum optical communication systems, high-speed communication, lightweight cryogenics for space crafts and biomedical use. In particular, high-temperature superconductors can allow for the development of superconducting nanowire single photon detectors (SNSPDs) that can operate at higher temperatures than standard superconductors, enhancing efficiency, simplicity of use, viability and affordability of the device in quantum computing, communications, and sensing. Despite this, it has to be pointed out that so far the fabrication of high temperature superconducting nanowires struggles to preserve good properties. Moreover, current state of the art sees the need for large and uniform detectors arrays formed by hundreds or thousands of detectors. As a results, the opportunity of modification of the detector metrics through post-processing gained more and more attention. In this thesis we try to investigate the effects of ion irradiation on superconductive nanowires single photon detectors. MgB2 and NbN have been chosen for our detectors and helium as irradiating ion. We were able to demonstrate the impact of different doses on the target materials as well as the ability of improving the detector metrics that could lead to the possibility of reaching homogeneous detector metrics after fabrication and on the same chip.