Transport studies of epi-Al/InAs 2DEG systems for required building-blocks in topological superconductor networks

TL;DR

This study demonstrates high-quality transport properties in epi-Al/InAs 2DEG heterostructures, showing potential for scalable topological superconductor networks capable of hosting Majorana zero modes for quantum computing.

Contribution

The paper presents detailed transport studies of epi-Al/InAs 2DEG systems, establishing their suitability for large-scale topological superconductor networks with multiple Majorana modes.

Findings

Observation of conductance plateaus at half-integer quanta due to strong spin-orbit coupling

High transparency of Al-InAs interface indicated by large IcRn product

Electronic transport results support the use of 2D heterostructures for quantum computing architectures

Abstract

One-dimensional (1D) electronic transport and induced superconductivity in semiconductor nano-structures are crucial ingredients to realize topological superconductivity. Our approach for topological superconductivity employs a two-dimensional electron gas (2DEG) formed by an InAs quantum well, cleanly interfaced with a superconductor (epitaxial Al). This epi-Al/InAs quantum well heterostructure is advantageous for fabricating large-scale nano-structures consisting of multiple Majorana zero modes. Here, we demonstrate building-block transport studies using a high-quality epi-Al/InAs 2DEG heterostructure, which could be put together to realize the proposed 1D nanowire-based nano-structures and 2DEG-based networks that could host multiple Majorana zero modes: 1D transport using 1) quantum point contacts and 2) gate-defined quasi-1D channels in the InAs 2DEG as well as induced superconductivity in 3) a ballistic Al-InAs 2DEG-Al Josephson junction. From 1D transport, systematic evolution of conductance plateaus in half-integer conductance quanta are observed as a result of strong spin-orbit coupling in the InAs 2DEG. Large IcRn, a product of critical current and normal state resistance from the Josephson junction, indicates that the interface between the epitaxial Al and the InAs 2DEG is highly transparent. Our results of electronic transport studies based on the 2D approach suggest that the epitaxial superconductor/2D semiconductor system is suitable for realizing large-scale nano-structures for quantum computing applications.