Thermal transport in nanoelectronic devices in the zero-temperature limit

On-chip demagnetization refrigeration has recently emerged as a powerful tool for reaching sub-mK temperatures in nanoscale electronic devices, and other miniaturized cooling techniques are being actively investigated. In the zero-temperature limit, the thermal subsystems in a device are decoupled from one another, and the resulting slow dynamics have remained largely unexplained. We study a Coulomb blockade thermometer, made from arrays of tunnel junctions with integrated on-chip copper refrigerant, both experimentally and numerically [1]. Comparing the two we show that dynamics in a multi-interface device cooled down to this temperature range are fully explained by a first-principles model. We can thus predict thermal dynamics in a generic device down to microkelvin temperatures. Our work outlines a low-investment recipe for bringing quantum technologies and fundamental nanoscience into this novel temperature range.

1. Autti et al., Phys. Rev. Lett. 131, 077001 (2023)