Absence of Quasi-Majorana False Positives in Full-Shell Hybrid Nanowires

TL;DR

Full-shell hybrid nanowires eliminate false positives in Majorana zero mode detection caused by smooth confinement, making tunneling spectroscopy a reliable identification method even with disorder.

Contribution

The study demonstrates that full-shell hybrid nanowires prevent quasi-Majorana false positives, unlike partial-shell nanowires, due to their unique topological properties.

Findings

Full-shell nanowires host a topologically trivial skin that blocks quasi-MZM detection.

True MZMs cause the trivial skin to disappear, enabling reliable tunneling spectroscopy.

This design improves the unambiguous detection of Majorana zero modes in disordered systems.

Abstract

Tunneling spectroscopy cannot be used as an unambiguous detection tool for Majorana zero modes (MZMs) in conventional partial-shell nanowires. The presence of smooth confinement at the end of the hybrid wire (among other sources of disorder) can create exponentially pinned zero-energy states, called quasi-MZMs, that mimic all local signatures of MZMs but lack topological protection. We find that this ambiguity in MZM detection does not occur in full-shell hybrid nanowires, an alternative nanowire design where a superconducting shell fully surrounds the semiconductor core. Acting as a synthetic vortex, a full-shell hybrid nanowire hosts Caroli-de Gennes-Matricon analog states. In the presence of smooth confinement, these states create a topologically trivial skin at the wire's end that prevents the local probe from detecting quasi-MZMs. Conversely, the trivial skin disappears when true MZMs form at the edge. This renders tunneling spectroscopy a reliable MZM detection technique for full-shell hybrid nanowires in the presence of smooth disorder.