Real-time milli-Kelvin thermometry in a semiconductor qubit architecture

TL;DR

This paper introduces a real-time thermometry technique for silicon nanowire quantum dot devices, enabling local temperature measurements with microsecond resolution to study thermal dynamics in quantum electronic systems.

Contribution

It presents two rf reflectometry-based measurement schemes for local electron and phonon thermometry with microsecond resolution, advancing thermal analysis in quantum devices.

Findings

Able to measure local temperatures with 3 mK/√Hz noise level

Tracked thermal excitation and relaxation dynamics after microwave heating

Revealed different characteristic time scales of thermal processes

Abstract

We report local time-resolved thermometry in a silicon nanowire quantum dot device designed to host a linear array of spin qubits. Using two alternative measurement schemes based on rf reflectometry, we are able to probe either local electron or phonon temperatures with $\mu$s-scale time resolution and a noise equivalent temperature of $3$ $\rm mK/\sqrt{\rm Hz}$. Following the application of short microwave pulses, causing local periodic heating, time-dependent thermometry can track the dynamics of thermal excitation and relaxation, revealing clearly different characteristic time scales. This work opens important prospects to investigate the out-of-equilibrium thermal properties of semiconductor quantum electronic devices operating at very low temperature. In particular, it may provide a powerful handle to understand heating effects recently observed in semiconductor spin-qubit systems.