Majorana bound states without vortices in topological superconductors with electrostatic defects

TL;DR

This paper proposes an alternative mechanism for Majorana bound states formation in topological superconductors, showing that electrostatic defects can host these states without vortices, expanding potential qubit applications.

Contribution

It introduces a Shockley-like mechanism for Majorana states at electrostatic defects, applicable even in topologically trivial phases, unlike vortex-based models.

Findings

Electrostatic line defects can host Majorana bound states at their ends.

Majorana states can appear without vortices, broadening the conditions for their realization.

The Shockley mechanism explains Majorana states in vortex-free models.

Abstract

Vortices in two-dimensional superconductors with broken time-reversal and spin-rotation symmetry can bind states at zero excitation energy. These socalled Majorana bound states transform a thermal insulator into a thermal metal and may be used to encode topologically protected qubits. We identify an alternative mechanism for the formation of Majorana bound states, akin to the way in which Shockley states are formed on metal surfaces: An atomic-scale electrostatic line defect can have a pair of Majorana bound states at the end points. The Shockley mechanism explains the appearance of a thermal metal in vortex-free lattice models of chiral p-wave superconductors and (unlike the vortex mechanism) is also operative in the topologically trivial phase.