Experimental Study of Magnetic Field Effects on Hairpin SNSPD Turn Designs for Single Photon Detection

Abstract

Superconducting Nanowire Single Photon Detectors (SNSPDs) are a promising technology for detecting single photon emissions with high efficiency and low noise. This detector class has numerous applications in quantum optics, communication, and sensing. One typical design for these devices is the hairpin structure, in which a superconducting nanowire is patterned into a meandering shape. The combination of academic research and interest from the industry is boosting the development of hairpin SNSPD devices to achieve high detection efficiency while maintaining fast response time and low jitter, requiring optimization of the device geometry, materials properties, and sophisticated readout electronics.

This thesis qualitatively enquires about different device geometries, varying turn designs and features. Moreover, proposing a promising experimental setup with the potential of being scaled up to simultaneously test numerous devices with a varying magnetic field, driving the hairpin SNSPDs to their detection limit, and enabling further quantitative studies to deepen the understanding of the underlying mechanisms currently hindering the SNSPDs. Analyzing the acquired data draws results regarding the critical current and dark counts trends. Furthermore, at low magnetic field strength, the enquired devices are found to have their critical current enhanced. Moreover, comparisons are drawn among similar design structures. Furthermore, a discussion on manufacturing defects detrimental to the SNSPD performance is initiated. Finally, further studies on this topic adopting the presented method are encouraged to acquire additional quantitative results to be compared with theoretical models describing the thin superconducting structures.