Using a quantum dot as a high-frequency shot noise detector

TL;DR

This paper demonstrates how a quantum dot can be used as a high-frequency shot noise detector, revealing quantum threshold effects and saturation phenomena, with implications for understanding backaction in charge detection.

Contribution

The study provides the first experimental realization of a quantum dot functioning as a high-frequency noise detector and offers a theoretical analysis of its behavior.

Findings

Detection of quantum threshold features

Observation of saturation in detector signal

Dependence of signal on QPC transmission and bias

Abstract

We present the experimental realization of a Quantum Dot (QD) operating as a high-frequency noise detector. Current fluctuations produced in a nearby Quantum Point Contact (QPC) ionize the QD and induce transport through excited states. The resulting transient current through the QD represents our detector signal. We investigate its dependence on the QPC transmission and voltage bias. We observe and explain a quantum threshold feature and a saturation in the detector signal. This experimental and theoretical study is relevant in understanding the backaction of a QPC used as a charge detector.