Counting statistics in an InAs nanowire quantum dot with a vertically coupled charge detector

TL;DR

This paper demonstrates charge detection and shot noise analysis in an InAs nanowire quantum dot coupled to a quantum point contact, revealing how tunneling barrier asymmetry influences electron transport.

Contribution

It introduces a novel setup combining a gate-defined InAs nanowire quantum dot with a vertically coupled charge detector for detailed charge and noise measurements.

Findings

Fano factor depends on tunneling barrier asymmetry as predicted.

Charge detection is effective even when thermal energy is comparable to level spacing.

Time-resolved charge detection provides insights into electron transport dynamics.

Abstract

A gate-defined quantum dot in an InAs nanowire is fabricated on top of a quantum point contact realized in a two-dimensional electron gas. The strong coupling between these two quantum devices is used to perform time-averaged as well as time-resolved charge detection experiments for electron flow through the quantum dot. We demonstrate that the Fano factor describing shot noise or time-correlations in single-electron transport depends in the theoretically expected way on the asymmetry of the tunneling barriers even in a regime where the thermal energy $k_\mathrm{B}T$ is comparable to the single-particle level spacing in the dot.