Controlling a quantum point junction on the surface of an antiferromagnetic topological insulator

TL;DR

This paper proposes a method to control quantum point junctions on the surface of antiferromagnetic topological insulators, enabling tunable edge-state interactions for potential quantum computing and sensing applications.

Contribution

It introduces a novel approach to create and manipulate quantum point junctions using the unique edge modes of antiferromagnetic topological insulators.

Findings

Distinct edge modes form robust quantum point junctions.

Surface modes can be controlled via magnetic and electrostatic tips.

Potential applications in quantum computing and sensing.

Abstract

The abstract notion of topology has led to profound insights into real materials. Notably, the surface and edges of topological materials can host physics, such as unidirectional charge or spin transport, that is unavailable in isolated one- and two-dimensional systems. However, to fully control the mixing and interference of edge-state wave functions, one needs robust and tunable junctions. We propose to achieve this control using an antiferromagnetic topological insulator that supports two distinct types of gapless unidirectional channels on its surface, one from antiferromagnetic domain walls and the other from single-height steps. The distinct geometric nature of these edge modes allows them to intersect robustly to form quantum point junctions, and their presence at the surface makes them subject to control by magnetic and electrostatic tips like those used in scanning probe microscopes. Prospects for realizing such junctions are encouraged by recent material candidate proposals, potentially leading to exciting applications in quantum computing and sensing.