Self-Heating Hotspots in Superconducting Nanowires Cooled by Phonon Black-Body Radiation

TL;DR

This paper demonstrates that electrical measurements can effectively estimate the thermal boundary conductance in superconducting nanowires, aligning with acoustic mismatch theory, thereby aiding thermal management in cryogenic superconducting devices.

Contribution

It introduces a simple electrical method to measure TBC in superconducting nanowires and validates it against theoretical models, filling a gap in systematic characterization.

Findings

Electrical measurements match acoustic mismatch theory for TBC.

Refined understanding through numerical simulations.

Method enables thermal engineering in superconducting devices.

Abstract

Controlling thermal transport is important for a range of devices and technologies, from phase change memories to next-generation electronics. This is especially true in nano-scale devices where thermal transport is altered by the influence of surfaces and changes in dimensionality. In superconducting nanowire single-photon detectors, the thermal boundary conductance (TBC) between the nanowire and the substrate it is fabricated on influences most of the performance metrics that make these detectors attractive for applications. This includes the maximum count rate, latency, jitter, and quantum efficiency. Despite its importance, the study of TBC in superconducting nanowire devices has not been done systematically, primarily due to the lack of a straightforward characterization method. Here, we show that simple electrical measurements can be used to estimate the TBC between nanowires and substrates and that these measurements match acoustic mismatch theory across a variety of substrates. Numerical simulations allow us to refine our understanding, however, open questions remain. This work should enable thermal engineering in superconducting nanowire electronics and cryogenic detectors for improved device performance.