Fast Single-Charge Sensing with an rf Quantum Point Contact

TL;DR

This paper demonstrates high-bandwidth, highly sensitive charge sensing using an rf-embedded quantum point contact, enabling rapid single-shot readout of quantum dots with minimal back-action.

Contribution

The work introduces a novel rf-QPC setup achieving fast, sensitive charge detection with high bandwidth and demonstrates its application in single-shot quantum dot readout.

Findings

Achieved conductance sensitivity of 5x10^(-6) e^2/h/Hz^{1/2}

Bandwidth of 8 MHz for charge sensing

Successful rapid switching of back-action during measurements

Abstract

We report high-bandwidth charge sensing measurements using a GaAs quantum point contact embedded in a radio frequency impedance matching circuit (rf-QPC). With the rf-QPC biased near pinch-off where it is most sensitive to charge, we demonstrate a conductance sensitivity of 5x10^(-6) e^(2)/h Hz^(-1/2) with a bandwidth of 8 MHz. Single-shot readout of a proximal few-electron double quantum dot is investigated in a mode where the rf-QPC back-action is rapidly switched.