Ebook: Technology and Readout for Scaling up Superconducting Nanowire Single-Photon Detectors

Detecting electromagnetic radiation at the quantum limit is essential for a wide range of applications, and superconducting nanowire single-photon detectors (SNSPDs) are among the highest-performing devices for this task. However, scaling SNSPDs from few-pixel devices to large detector arrays while preserving their beneficial metrics remains challenging.

In this work, three advances toward the realization of SNSPD arrays are presented. Atomic layer deposition is employed to enable uniform superconducting niobium nitride films of only few-nanometer thickness suitable for large-area devices. To operate and read out multiple detectors with a reduced number of lines, a frequency-multiplexing scheme is investigated, in particular regarding its effect on the resetting behavior and duty cycle of the detector. Finally, efficient optical coupling from free space and optical fibers onto the active area of the detectors is achieved by directly integrating SNSPDs with free-form polymer structures.