Split-gate quantum point contacts with tunable channel length

TL;DR

This paper presents a novel split-gate quantum point contact design with tunable channel length in a GaAs/AlGaAs heterostructure, enabling precise control over electron transport properties for advanced quantum studies.

Contribution

Introduces a six-gate finger design for QPCs that allows dynamic tuning of the channel length from 200 nm to 600 nm, enhancing control over quantum transport phenomena.

Findings

Channel length can be tuned from 200 nm to 600 nm

Electrostatic simulations match experimental results

Design improves control over electron many-body effects

Abstract

We report on developing split-gate quantum point contacts (QPCs) that have a tunable length for the transport channel. The QPCs were realized in a GaAs/AlGaAs heterostructure with a two- dimensional electron gas (2DEG) below its surface. The conventional design uses 2 gate fingers on the wafer surface which deplete the 2DEG underneath when a negative gate voltage is applied, and this allows for tuning the width of the QPC channel. Our design has 6 gate fingers and this provides additional control over the form of the electrostatic potential that defines the channel. Our study is based on electrostatic simulations and experiments and the results show that we developed QPCs where the effective channel length can be tuned from about 200 nm to 600 nm. Length-tunable QPCs are important for studies of electron many-body effects because these phenomena show a nanoscale dependence on the dimensions of the QPC channel.