Single Shot Charge Detection Using A Radio-Frequency Quantum Point Contact

TL;DR

This paper demonstrates a radio-frequency quantum point contact (rf-QPC) for single-shot charge detection in GaAs quantum dots, achieving high bandwidth and sensitivity, and showing promise for fast quantum system measurements.

Contribution

It introduces a fully characterized rf-QPC with high bandwidth and sensitivity for charge sensing, outperforming traditional rf-SET electrometers.

Findings

Bandwidth exceeds 20 MHz

Charge sensitivity of 2x10^-4 e/√Hz

Comparable or better performance than rf-SET electrometers

Abstract

We report on charge sensing measurements of a GaAs semiconductor quantum dot device using a radio frequency quantum point contact (rf-QPC). The rf-QPC is fully characterized at 4 K and milli-Kelvin temperatures and found to have a bandwidth exceeding 20 MHz. For single-shot charge sensing we achieve a charge sensitivity of 2x10^-4 e/(sqrt)Hz referred to the neighboring dot's charge. The rf-QPC compares favorably with rf-SET electrometers and promises to be an extremely useful tool for characterizing and measuring semiconductor quantum systems on fast timescales.