Primary thermometry triad at 6 mK in mesoscopic circuits

TL;DR

This paper demonstrates electronic quantum transport at 6 mK in mesoscopic circuits using three in-situ primary thermometers, advancing the understanding of ultra-low temperature physics in mesoscopic systems.

Contribution

It introduces a novel thermometry triad combining three different quantum-based methods to accurately measure ultra-low temperatures in mesoscopic circuits.

Findings

Achieved electronic quantum transport at 6 mK in mesoscopic circuits.

Validated thermometry methods across a broad spectrum of mesoscopic phenomena.

Paved the way for reaching sub-millikelvin temperatures with improved thermalization.

Abstract

Quantum physics emerge and develop as temperature is reduced. Although mesoscopic electrical circuits constitute an outstanding platform to explore quantum behavior, the challenge in cooling the electrons impedes their potential. The strong coupling of such micrometer-scale devices with the measurement lines, combined with the weak coupling to the substrate, makes them extremely difficult to thermalize below 10 mK and imposes in-situ thermometers. Here we demonstrate electronic quantum transport at 6 mK in micrometer-scale mesoscopic circuits. The thermometry methods are established by the comparison of three in-situ primary thermometers, each involving a different underlying physics. The employed combination of quantum shot noise, quantum back-action of a resistive circuit and conductance oscillations of a single-electron transistor covers a remarkably broad spectrum of mesoscopic phenomena. The experiment, performed in vacuum using a standard cryogen-free dilution refrigerator, paves the way toward the sub-millikelvin range with additional thermalization and refrigeration techniques.