Published in PRAppl: Cryogenic hyperabrupt strontium titanate varactors for sensitive reflectometry of quantum dots
Radio frequency reflectometry for qubit readout enables high bandwidth but requires careful impedance matching which is challenging to do in-situ at mK temperatures due to freeze-out of GaAs varactors. In this manuscript, we present a design employing strontium titanate high-k material giving hyperabrupt capacitance-voltage characteristics which is compact, scalable and easy to wirebond. We tune a resonant inductor-capacitor circuit to perfect impedance matching and observe robust, temperature and field independent matching down to 11mK and up to 2T in-plane field. Finally, we perform gate-dispersive charge sensing on a Ge/Si core/shell nanowire hole double quantum dot, paving the way towards gate-based single-shot spin readout.
Supported by NCCR SPIN of the Swiss NSF.
Cryogenic hyperabrupt strontium titanate varactors for sensitive reflectometry of quantum dots
Rafael S. Eggli*, Simon Svab*, Taras Patlatiuk, Dominique Trüssel, Miguel J. Carballido, Pierre Chevalier Kwon, Simon Geyer, Ang Li, Erik P. A. M. Bakkers, Andreas V. Kuhlmann, Dominik M. Zumbühl,
Phys. Rev. Appl. 20, 054056 (Nov 28, 2023), manuscript pdf