Abstract
Temperatures below 1 mK on-chip hold great potential for quantum physics but present a great challenge due to the lack of suitable thermometry and the detrimental pulse-tube vibrations of cryogen-free refrigerators. Here, we solve the pulse-tube problem using a rigidly wired metallic sample holder, which provides a microkelvin environment with low heat leaks despite the vibrations. Further, we demonstrate an improved type of temperature sensor, the gate Coulomb blockade thermometer (gCBT), employing a gate metallization covering the entire device. This immunizes against nanofabrication imperfections and uncontrollable offset charges, and extends the range to lower temperatures compared to a junction CBT with the same island capacitance, here down to ≈160 μK for a 10% accuracy. Using on- and off-chip cooling, we demonstrate electronic temperatures as low as 224 ± 7 μK, remaining below 300 μK for 27 hours, thus providing time for experiments. Finally, we give an outlook for cooling below 50 μK for a future generation of microkelvin transport experiments.
| Original language | English |
|---|---|
| Article number | 033225 |
| Journal | Physical review research |
| Volume | 4 |
| Issue number | 3 |
| DOIs | |
| Publication status | Published - Jul 2022 |
| MoE publication type | A1 Journal article-refereed |
Funding
This research was supported by the EU H2020 European Microkelvin Platform (EMP) Grant No. 824109, innovation program under Grant Agreement No. 766853 Energy Filtering Non-Equilibrium Devices (EFINED), MSCA Cofund Action Quantum Science and Technologies at the European Campus (QUSTEC) Grant No. 847471, and by the Academy of Finland through the Centre of Excellence Programs No. 336817 and No. 312294, the Swiss National Science Foundation Grant No. 179024, the Swiss Nanoscience Institute, and the Georg H. Endress Foundation.
