Topological superconductor with a large Chern number and a large bulk excitation gap in single layer graphene

TL;DR

This paper proposes a method to realize a two-dimensional topological superconductor with a high Chern number and a large bulk excitation gap in single-layer graphene, enabling robust Majorana modes for quantum computing.

Contribution

It demonstrates that a hybrid system with proximity-induced superconductivity in quantum anomalous Hall states in graphene can host a topological superconductor with a large Chern number and a sizable bulk gap.

Findings

Achieves a Chern number of four supporting four Majorana modes.

Shows the bulk excitation gap can be much larger than the superconducting gap.

Provides a pathway for robust topological quantum computation.

Abstract

We show that a two-dimensional topological superconductor (TSC) can be realized in a hybrid system with a conventional $s$-wave superconductor proximity-coupled to a quantum anomalous Hall (QAH) state from the Rashba and exchange effects in single layer graphene. With very low or even zero doping near the Dirac points, i.e., two inequivalent valleys, this TSC has a Chern number as large as four, which supports four Majorana edge modes. More importantly, we show that this TSC has a robust topologically nontrivial bulk excitation gap, which can be larger or even one order of magnitude larger than the proximity-induced superconducting gap. This unique property paves a way for the application of QAH insulators as seed materials to realize robust TSCs and Majorana modes.