Two-dimensional platform for networks of Majorana bound states

TL;DR

This paper proposes a two-dimensional platform for creating and controlling networks of Majorana bound states in a superconductor-2DEG system, enabling potential quantum computing applications.

Contribution

It introduces a method to form topological channels by removing superconducting stripes and demonstrates control over Majorana states using phase differences or gating.

Findings

Topological superconducting channels are formed in 2DEG with superconducting stripes.

The topological gap is enhanced by structural asymmetry.

Control over MBS splitting is achieved via phase difference or gating.

Abstract

We model theoretically a two-dimensional electron gas (2DEG) covered by a superconductor and demonstrate that topological superconducting channels are formed when stripes of the superconducting layer are removed. As a consequence, Majorana bound states (MBS) are created at the ends of the stripes. We calculate the topological invariant and energy gap of a single stripe, using realistic values for an InAs 2DEG proximitized by an epitaxial Al layer. We show that the topological gap is enhanced when the structure is made asymmetric. This can be achieved by either imposing a phase difference (by driving a supercurrent or using a magnetic-flux loop) over the strip or by replacing one superconductor by a metallic gate. Both strategies also enable control over the MBS splitting, thereby facilitating braiding and readout schemes based on controlled fusion of MBS. Finally, we outline how a network of Majorana stripes can be designed.