InSbAs two-dimensional electron gases as a platform for topological superconductivity

Majorana zero-modes (MZMs), building blocks of topologically protected qubits, can be realized in semiconductors with strong spin-orbit interaction coupled to a superconductor. Among the candidate systems, hybrid two-dimensional electron gases (2DEGs) are of particular interest due to their inherent design flexibility and scalability.
Here, we discuss results on a new hybrid 2D platform consisting of a ternary 2DEG (InSbAs) coupled to epitaxially grown Aluminum. We show that this ternary has a large Landé g-factor of ~50, along with exceptionally strong spin-orbit coupling, exceeding the value for both InSb and InAs. Furthermore, the strength of this spin-orbit interaction is tuneable by the As concentration, in good agreement with theoretical predictions. Through spectroscopic measurements we show that the induced superconducting gap in this hybrid system is hard with a value close to that of bare Aluminum. The pristine semiconductor-superconductor interface is further confirmed by the observation of highly transparent Josephson junctions that can be used to create phase-controllable MZMs in a SQUID geometry.
These results establish InSbAs/Al 2DEGs as a promising new material system to realize topological superconductivity.