Majorana quasiparticles of inhomogeneous Rashba chain

TL;DR

This paper studies Majorana quasiparticles in an inhomogeneous Rashba chain coupled to a superconductor, analyzing their robustness against disorder and their non-local nature, with implications for quantum information applications.

Contribution

It provides a detailed analysis of the stability and non-locality of Majorana quasiparticles in disordered Rashba chains, highlighting their potential for quantum technologies.

Findings

Majorana quasiparticles are robust against certain types of disorder.

Disorder can induce a topological phase transition detectable via local spectra.

Majorana quasiparticles exhibit non-local properties and can spread through proximity effects.

Abstract

We investigate the inhomogeneous Rashba chain coupled to a superconducting substrate, hosting the Majorana quasiparticles near its edges. We discuss its subgap spectrum and study how robust are the zero-energy quasiparticles against the diagonal and off-diagonal disorder. Studying the $\mathbb{Z}_2$ topological invariant we show that disorder induced transition from the topologically non-trivial to trivial phases is manifested by characteristic features in the spatially-resolved quasiparticle spectrum at zero energy. We provide evidence for the non-local nature of the zero-energy Majorana quasiparticles, that are well preserved upon partitioning the chain into separate pieces. Even though the Majorana quasiparticles are not completely immune to inhomogeneity we show that they can spread onto other (normal) nanoscopic objects via the proximity effect.