A number of groups worldwide are working to produce sub-millikelvin on-chip electron temperatures, motivated by the possibility to observe new physics and improving quantum device performance. In this review, we focus on on-chip demagnetisation refrigeration, which was used by multiple groups to reach temperatures around 1mK, with a current record below 0.5 mK. https://arxiv.org/abs/2001.07419
We experimentally demonstrate an algorithm capable of fine-tuning several device parameters at once. The algorithm acquires a measurement, scores it using a variational auto-encoder, and optimizes gate voltage via the score in real-time in an unsupervised fashion. https://arxiv.org/abs/2001.04409
We introduce a new spin quantization axis via the persistent spin helix, revealing a full decoupling of the Cooperon triplet scattering modes as well as decoupled Landau levels. This makes it possible to derive a closed-form expression for the weak localization magnetoconductivity, thus providing a new paradigm of localization in the weakly-broken spin symmetry regime.
Weigele et al., PRB101, 035414 (Jan 16, 2020).
Asser Elsayed from the group of Dr. Iuliana Radu and Dr. Bogdan Govoreanu, Imec Leuven, Belgium, is starting a user access project on the Basel node of the European Microkelvin Platform (EMP). The project is working to develop Si and GeSi materials for spin qubit applications.
We demonstrate a statistical tuning algorithm that navigates the entire large parameter space of a gate-defined quantum dot. Using just a few modelling assumptions, we demonstrate fully automated tuning to the double dot regime.This also makes possible to give a quantitative measurement of device variability, from device to device, and also after thermal cycles. https://arxiv.org/abs/2001.02589