Vortex-parity-controlled diode effect in Corbino topological Josephson junctions

TL;DR

This paper demonstrates a vortex-parity-controlled Josephson diode effect in topological insulator-based Corbino junctions, revealing a unique interplay between vortex parity and topological superconductivity that could inform future quantum device designs.

Contribution

It reports the first observation of an even-odd vortex parity-dependent Josephson diode effect in topological insulator junctions, linking it to topological superconductivity and vortex-bound states.

Findings

Diode polarity alternates with vortex parity in 3DTI Corbino junctions.

The effect is absent in non-topological and linear junction controls.

Theoretical modeling connects the effect to boundary conditions and topological Andreev states.

Abstract

Nonreciprocal supercurrents in Josephson junctions have recently emerged as a sensitive tool for investigating broken symmetries in superconducting quantum materials. Here, we report an even-odd Josephson diode effect (JDE) in Corbino-geometry junctions fabricated on the pristine surface of a bulk-insulating three-dimensional topological insulator (3DTI). We find that the diode polarity, which indicates the preferred direction of supercurrent flow, robustly alternates its sign depending on the parity (even or odd) of the enclosed vortex number. This behavior is absent in two key control devices: a non-topological graphene Corbino Josephson junction and a 3DTI-based linear Josephson junction. These results indicate that the polarity-tunable JDE is intrinsically linked to the unique combination of the proximitized topological superconductivity in the 3DTI surface and the Corbino device's closed-loop geometry. Our theoretical modeling attributes the observed sign change in diode polarity to the alternating sign of periodic boundary conditions in topological superconductors, supporting the interpretation that the vortex-parity-controlled JDE is a direct manifestation of the underlying Andreev bound state topology associated with the presence of non-Abelian anyons in the vortices.