Majorana fermions in pinned vortices

TL;DR

This paper proposes a device using topological insulators and superconductivity to create and detect robust Majorana fermions inside vortex cores, with potential for quantum computing applications.

Contribution

It analytically demonstrates the creation of a stable Majorana fermion in vortex cores with a large energy gap, enhancing robustness against thermal fluctuations.

Findings

Majorana fermion state is separated by a large energy gap from other excitations.

The Majorana state can be detected via zero-bias conductance peaks.

The system remains robust at temperatures below the superconducting critical temperature.

Abstract

Exploiting the peculiar properties of proximity-induced superconductivity on the surface of a topological insulator, we propose a device which allows the creation of a Majorana fermion inside the core of a pinned Abrikosov vortex. The relevant Bogolyubov-de Gennes equations are studied analytically. We demonstrate that in this system the zero-energy Majorana fermion state is separated by a large energy gap, of the order of the zero-temperature superconducting gap $\Delta$, from a band of single-particle non-topological excitations. In other words, the Majorana fermion remains robust against thermal fluctuations, as long as the temperature remains substantially lower than the critical superconducting temperature. Experimentally, the Majorana state may be detected by measuring the tunneling differential conductance at the center of the Abrikosov vortex. In such an experiment, the Majorana state manifests itself as a zero-bias anomaly separated by a gap, of the order of $\Delta$, from the contributions of the nontopological excitations.