Time-resolved charge detection with cross-correlation techniques

TL;DR

This paper introduces a cross-correlation method for time-resolved charge detection in quantum dots, reducing noise sensitivity and invasiveness, thereby enhancing measurement bandwidth in quantum sensing applications.

Contribution

It demonstrates a novel cross-correlation technique for charge sensing that improves detection sensitivity and reduces invasiveness compared to traditional single-QPC methods.

Findings

Effective charge detection at lower signal-to-noise ratios

Reduced detector current levels to minimize invasiveness

Potential for increased measurement bandwidth

Abstract

We present time-resolved charge sensing measurements on a GaAs double quantum dot with two proximal quantum point contact (QPC) detectors. The QPC currents are analyzed with cross-correlation techniques, which enables us to measure dot charging and discharging rates for significantly smaller signal-to-noise ratios than required for charge detection with a single QPC. This allows to reduce the current level in the detector and therefore the invasiveness of the detection process and may help to increase the available measurement bandwidth in noise-limited setups.