Few-electron Single and Double Quantum Dots in an InAs Two-Dimensional Electron Gas

TL;DR

This paper reports the first realization of high-quality single and double quantum dots in an InAs 2DEG, demonstrating precise control over few-electron regimes and revealing key spin properties relevant for quantum computing.

Contribution

It introduces a novel InAs 2DEG quantum dot platform with long spin-orbit length and strong control, advancing spin qubit research beyond GaAs-based systems.

Findings

Observation of the Kondo effect and singlet-triplet spin blockade.

Measurement of an electronic g-factor of 16.

Estimation of a long spin-orbit length (~5-10 μm).

Abstract

Most proof-of-principle experiments for spin qubits have been performed using GaAs-based quantum dots because of the excellent control they offer over tunneling barriers and the orbital and spin degrees of freedom. Here, we present the first realization of high-quality single and double quantum dots hosted in an InAs two-dimensional electron gas (2DEG), demonstrating accurate control down to the few-electron regime, where we observe a clear Kondo effect and singlet-triplet spin blockade. We measure an electronic $g$-factor of $16$ and a typical magnitude of the random hyperfine fields on the dots of $\sim 0.6\, \mathrm{mT}$. We estimate the spin-orbit length in the system to be $\sim 5-10\, \mu \mathrm{m}$, which is almost two orders of magnitude longer than typically measured in InAs nanostructures, achieved by a very symmetric design of the quantum well. These favorable properties put the InAs 2DEG on the map as a compelling host for studying fundamental aspects of spin qubits. Furthermore, having weak spin-orbit coupling in a material with a large Rashba coefficient potentially opens up avenues for engineering structures with spin-orbit coupling that can be controlled locally in space and/or time.