Core-shell nanowires as a platform for topological superconductivity

The hunt for new topological materials has attracted a tremendous amount of attention in recent years.

One of the most sought-after properties is topological superconductivity, hosting Majorana bound states that could be used for topologically protected quantum computing schemes.

In this project, we propose and theoretically investigate a new topological superconductor, consisting of a semiconductor core-shell nanowire, together with proximity induced superconductivity. The material system of InAs and GaSb is known to be a topological insulator. In two dimensions it can be tuned between the topological and trivial regime by tuning of the material thicknesses.

In core-shell nanowires similar tuning is possible, but in one dimension the system is never topological. However, with proximity-induced superconductivity the system would be a topological superconductor.

We will calculate the spectrum and topological invariants of this system, and prove how these are affected by shell thicknesses.

We will develop novel computational methods to take both the material properties and the superconductivity into account.

To understand the properties of the system in setups relevant for experiments and future applications we investigate its transport properties, both as an elongated nanowire, but also as quantum dots in shorter wire segments and as part of a nanowire network. Our results will show if and when Majorana bound states are present, and how they are affected by their environment.