Radio-Frequency Reflectometry in Silicon-Based Quantum Dots

Abstract

Radio-frequency (rf) reflectometry offers a fast and sensitive method for charge sensing and spin readout in gated quantum dots. We focus in this work on the implementation of rf readout in accumulation-mode gate-defined quantum dots, where the large parasitic capacitance poses a challenge. We describe and test two methods for mitigating the effect of the parasitic capacitance, one by on-chip modifications and a second by off-chip changes. We demonstrate that on-chip modifications enable high-performance charge readout in $\mathrm{Si}$/${\mathrm{Si}}_{x}$${\mathrm{Ge}}_{1\ensuremath{-}x}$ quantum dots, achieving a fidelity of 99.9% for a measurement time of $1\phantom{\rule{0.2em}{0ex}}\ensuremath{\mu}\mathrm{s}$.