Ballistic Majorana nanowire devices

TL;DR

This paper demonstrates clear signatures of Majorana modes in ballistic InSb nanowire devices, providing strong evidence for topological superconductivity and overcoming disorder-related challenges in previous experiments.

Contribution

It reports the first observation of Majorana signatures in ballistic nanowires with controlled parameters, excluding disorder as an alternative explanation.

Findings

Zero bias peaks are stable over large parameter regions.

Distinct topological phases are identified through parameter space mapping.

Results align with Majorana theory in ballistic systems.

Abstract

Majorana modes are zero-energy excitations of a topological superconductor that exhibit non-Abelian statistics. Following proposals for their detection in a semiconductor nanowire coupled to an s-wave superconductor, several tunneling experiments reported characteristic Majorana signatures. Reducing disorder has been a prime challenge for these experiments because disorder can mimic the zero-energy signatures of Majoranas, and renders the topological properties inaccessible. Here, we show characteristic Majorana signatures in InSb nanowire devices exhibiting clear ballistic transport properties. Application of a magnetic field and spatial control of carrier density using local gates generates a zero bias peak that is rigid over a large region in the parameter space of chemical potential, Zeeman energy, and tunnel barrier potential. The reduction of disorder allows us to resolve separate regions in the parameter space with and without a zero bias peak, indicating topologically distinct phases. These observations are consistent with the Majorana theory in a ballistic system, and exclude for the first time the known alternative explanations that invoke disorder or a nonuniform chemical potential.