A microkelvin cryogen-free experimental platform with integrated noise thermometry

TL;DR

This paper demonstrates a cryogen-free platform capable of reaching temperatures below 1 millikelvin, using integrated noise thermometry and nuclear magnetic cooling, with potential applications in quantum computing.

Contribution

It introduces a novel cryogen-free microkelvin cooling system with integrated noise thermometry, achieving stable sub-millikelvin temperatures.

Findings

Achieved 600 μK temperature with residual heat leak of 5 nW.

Maintained below 1 mK for over 24 hours.

Proposed design improvements for enhanced performance.

Abstract

We report experimental demonstration of the feasibility of reaching temperatures below 1 mK using cryogen-free technology. Our prototype system comprises an adiabatic nuclear demagnetisation stage, based on hyperfine-enhanced nuclear magnetic cooling, integrated with a commercial cryogen-free dilution refrigerator and 8 T superconducting magnet. Thermometry was provided by a current-sensing noise thermometer. The minimum temperature achieved at the experimental platform was 600 {\mu}K. The platform remained below 1 mK for over 24 hours, indicating a total residual heat-leak into the experimental stage of 5 nW. We discuss straightforward improvements to the design of the current prototype that are expected to lead to enhanced performance. This opens the way to widening the accessibility of temperatures in the microkelvin regime, of potential importance in the application of strongly correlated electron states in nanodevices to quantum computing.