Experiments performed at a temperature of a few millikelvin require effective thermalization schemes, low-pass filtering of the measurement lines and low-noise electronics. Here, we report on the modifications to a commercial dilution refrigerator with a base temperature of 3.5 mK that enable us to lower the electron temperature to 6.7 mK measured from the Coulomb peak width of a quantum dot gate-defined in an [Al]GaAs heteostructure. We present the design and implementation of a liquid 4He immersion cell tight against superleaks, implement an innovative wiring technology and develop optimized transport measurement procedures.
@article{arxiv.1909.10906,
title = {Quantum dot thermometry at ultra-low temperature in a dilution refrigerator with a $^4$He immersion cell},
author = {Giorgio Nicolí and Peter Märki and Beat A. Bräm and Marc P. Röösli and Szymon Hennel and Andrea Hofmann and Christian Reichl and Werner Wegscheider and Thomas Ihn and Klaus Ensslin},
journal= {arXiv preprint arXiv:1909.10906},
year = {2019}
}