Topological Phase Transitions of Superconducting Vortex Bound States Driven by Impurities

TL;DR

This paper demonstrates that impurities can induce topological phase transitions in vortex bound states of superconductors, potentially enabling Majorana modes in vortex systems, with implications for quantum computing.

Contribution

It reveals how impurities can drive topological transitions in vortex bound states, highlighting superconducting vortices as a platform for Majorana modes.

Findings

Impurities induce topological phase transitions in vortex bound states.

Vortex bound states can host Majorana modes, including zero and propagating modes.

Impurity chains can drive 3D vortex states into topologically nontrivial phases.

Abstract

We show that standard impurities, magnetic or nonmagnetic, weak or strong, can cause topological phase transitions inside the vortex cores of a conventional s-wave superconductor. Because of the nonzero angular momentum of Cooper pairs in the vortex cores, the vortex bound states in a two dimensional superconductor are sensitive to impurities in a way similar to the Yu-Shiba-Rusinov bound states induced by magnetic impurities. In three dimensional cases, the vortex bound states can be driven into topologically nontrivial phases by an impurity chain inside the vortex core. The system can host Majorana modes including the Majorana zero modes localized at the end of the vortex line and the propagating Majorana modes along the vortex line. These results suggest that the superconducting vortex can be the simplest platform to realize Majorana modes.