Progress in superconductor-semiconductor topological Josephson junctions

TL;DR

This paper reviews progress in creating topological Josephson junctions using superconductor-semiconductor interfaces, emphasizing the potential for realizing Majorana bound states and the need for advanced experiments like braiding.

Contribution

It provides an overview of current methods and insights into how to advance experimental realization of Majorana bound states in superconductor-semiconductor systems.

Findings

Epitaxial superconductor-semiconductor interfaces enable topological states.

Current experiments have not yet observed non-Abelian braiding.

Future work should focus on braiding and fusion experiments for MBS detection.

Abstract

Majorana bound states (MBSs) are quasiparticles which are their own antiparticles. They are predicted to emerge as zero-energy modes localized at the boundary of a topological superconductor. No intrinsic topological superconductor is known to date. However, by interfacing conventional superconductors and semiconductors with strong spin--orbit coupling it is possible to create a system hosting topological states. Hence epitaxial superconductors and semiconductors have emerged as an attractive materials system with atomically sharp interfaces and broad flexibility in device fabrications incorporating Josephson junctions. We discuss the basics of topological superconductivity and provide insight on how to go beyond current state-of-the-art experiments. We argue that the ultimate success in realizing MBS physics requires the observation of non-Abelian braiding and fusion experiments.