Radio-Frequency Charge Detection on Graphene Electron-Hole Double Quantum Dots

Abstract

High-fidelity detection of charge transitions in quantum dots (QDs) is a key ingredient in solid-state quantum computation. We demonstrate high-bandwidth radio-frequency charge detection in bilayer graphene quantum dots (QDs) using a capacitively coupled quantum point contact (QPC). The device design suppresses screening effects and enables a sensitive QPC-based charge readout. The QPC is arranged to maximize the readout contrast between two neighboring coupled electron and hole QDs. We apply the readout scheme to a single-particle electron-hole double QD and demonstrate time-resolved detection of charge states as well as magnetic field dependent tunneling rates. This promises a high-fidelity readout scheme for individual spin and valley states, which is important for the operation of spin, valley, or spin-valley qubits in bilayer graphene.