Majorana dc Josephson current mediated by a quantum dot

TL;DR

This paper investigates the supercurrent in a Majorana-quantum dot-Majorana junction, revealing unique behaviors influenced by spin-selective coupling and topological phase effects, with implications for future Majorana-based circuits.

Contribution

It introduces a detailed analysis of the supercurrent in a Majorana-quantum dot system, highlighting the effects of spin-selective coupling and topological phases on current behavior.

Findings

Supercurrent behaviors differ from normal resonant tunneling.

Spin-selective coupling influences supercurrent in topological phase.

Both 2π and 4π periodic currents are analyzed.

Abstract

The Josephson supercurrent through the hybrid Majorana--quantum dot--Majorana junction is investigated. We particularly analyze the effect of spin-selective coupling between the Majorana and quantum dot states, which emerges only in the topological phase and will influence the current through bent junctions and/or in the presence of magnetic fields in the quantum dot. We find that the characteristic behaviors of the supercurrent through this system are quite counterintuitive, remarkably differing from the resonant tunneling, e.g., through the similar (normal phase) superconductor--quantum dot--superconductor junction. Our analysis is carried out under the influence of full set-up parameters and for both the $2\pi$ and $4\pi$ periodic currents. The present study is expected to be relevant to future exploration of applications of the Majorana-nanowire circuits.