Topological Josephson Junctions in the Integer Quantum Hall Regime

TL;DR

This paper proposes a robust, tunable topological Josephson junction in the integer quantum Hall regime, offering insights into its spectrum and potential for quantum computing applications, with advantages over existing hybrid systems.

Contribution

It introduces a new electrostatically tunable TJJ in the IQH regime, combining analytical insights and demonstrating protected zero-energy crossings controllable by external gates.

Findings

Existence of protected zero-energy crossings in the spectrum.

Electrostatic tunability allows compensation for interface imperfections.

Potential implementation in graphene and 2D materials for quantum applications.

Abstract

Robust and tunable topological Josephson junctions (TJJs) are highly desirable platforms for investigating the anomalous Josephson effect and topological quantum computation applications. Experimental demonstrations have been done in hybrid superconducting-two dimensional topological insulator (2DTI) platforms, sensitive to magnetic disorder and interactions with phonons and other electrons. In this work, we propose a robust and electrostatically tunable TJJ by combining the physics of the integer quantum Hall (IQH) regime and of superconductors. We provide analytical insights about the corresponding Andreev bound state spectrum, the Josephson current and the anomalous current. We demonstrate the existence of protected zero-energy crossings, that can be controlled through electrostatic external gates. This electrostatic tunability has a direct advantage to compensate for non-ideal interfaces and undesirable reflections that may occur in any realistic samples. TJJs in the IQH regime could be realized in graphene and other 2D materials. They are of particular relevance towards scalable and robust Andreev-qubit platforms, and also for efficient phase batteries.