Quantum Measurements with Superconducting Nanowire Single Photon Detectors

Citation

Mueller, Andrew Sterling (2024) Quantum Measurements with Superconducting Nanowire Single Photon Detectors. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/tneb-9z27. https://resolver.caltech.edu/CaltechTHESIS:02092024-210936211

Abstract

Superconducting Nanowire Single-Photon Detectors (SNSPDs) are high-performance photon counting detectors, typically operated just a few degrees above absolute zero. Comprising a current-biased nanowire transitioning between superconducting and resistive states upon photon absorption, SNSPDs generate voltage pulses for precise photon arrival time measurement. Initially demonstrated in the 1990s, SNSPDs are now mature devices widely employed in various fields, including space communication, biological imaging, and quantum technology. This thesis explores techniques to enhance usable count rate, dark count rate, timing resolution, and photon number resolution for both emerging and established SNSPD designs. We introduce a free space optical filtering method to minimize SNSPD dark count rates which is competitive with the state-of-the-art for fiber coupled SNSPDs, and especially impactful for space communication applications. We go on to study dynamics that limit SNSPD maximum count rates, presenting a calibration and in-situ correction procedure to significantly reduce jitter at high rates without additional hardware or offline processing. With an eye towards space communication applications beyond NASA's Deep Space Optical Communication (DSOC) project, we present a high-rate Pulse Position Modulation communication demo with SNSPDs. In the process we uncover a rich photon-number dependent response in these detectors and devise methods to properly leverage and manage it. Finally, we employ low-jitter SNSPDs in a high-rate entanglement distribution system, achieving high entanglement visibilities, and distillable entanglement rates.  As this work focuses on optimizing SNSPD usage and analysis rather than device physics or fabrication, it is broadly applicable to any users of this single photon detection technology.

Thesis Files