Quantized conductance in a one-dimensional ballistic oxide nanodevice

TL;DR

This paper reports the observation of quantized conductance in a ballistic oxide nanodevice, specifically a LaAlO3/SrTiO3 quantum point contact, advancing the understanding of quantum transport in oxide interfaces.

Contribution

It demonstrates the fabrication and spectroscopic analysis of a nanoscale oxide quantum point contact exhibiting conductance quantization, a significant step in oxide quantum device development.

Findings

Observation of conductance quantization in oxide nanodevice

Spectroscopic probing of 3d energy levels in the QPC

Potential for detecting Majorana states in oxide 2-DEG

Abstract

Electric-field effect control of two-dimensional electron gases (2-DEG) has enabled the exploration of nanoscale electron quantum transport in semiconductors. Beyond these classical materials, transition metal-oxide-based structures have d-electronic states favoring the emergence of novel quantum orders absent in conventional semiconductors. In this context, the LaAlO3/SrTiO3 interface that combines gate-tunable superconductivity and sizeable spin-orbit coupling is emerging as a promising platform to realize topological superconductivity. However, the fabrication of nanodevices in which the electronic properties of this oxide interface can be controlled at the nanoscale by field-effect remains a scientific and technological challenge. Here, we demonstrate the quantization of conductance in a ballistic quantum point contact (QPC), formed by electrostatic confinement of the LaAlO3/SrTiO3 2-DEG with a split-gate. Through finite source-drain voltage, we perform a comprehensive spectroscopic investigation of the 3d energy levels inside the QPC, which can be regarded as a spectrometer able to probe Majorana states in an oxide 2-DEG.