Dispersive Readout of a Few-Electron Double Quantum Dot with Fast rf Gate Sensors

Abstract

We report the dispersive charge-state readout of a double quantum dot in the few-electron regime using the in situ gate electrodes as sensitive detectors. We benchmark this gate sensing technique against the well established quantum point contact charge detector and find comparable performance with a bandwidth of $\ensuremath{\sim}10\text{ }\text{ }\mathrm{MHz}$ and an equivalent charge sensitivity of $\ensuremath{\sim}6.3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}\text{ }\text{ }e/\sqrt{\mathrm{Hz}}$. Dispersive gate sensing alleviates the burden of separate charge detectors for quantum dot systems and promises to enable readout of qubits in scaled-up arrays.