EMP is funded through the Horizon2020 programme of the European Commission.
Selected Publications

Microkelvin electronics on a pulse-tube cryostat with a gate Coulomb blockade thermometer

Mohammad Samani, Christian P. Scheller, Omid Sharifi Sedeh, Dominik M. Zumbühl, Nikolai Yurttagül, Kestutis Grigoras, David Gunnarsson, Mika Prunnila, Alexander T. Jones, Jonathan R. Prance, and Richard P. Haley

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.

Phys. Rev. Research 4, 033225

doi: 10.1103/PhysRevResearch.4.033225