Interaction induced hybridization of Majorana zero-modes in a coupled quantum-dot hybrid-nanowire system

TL;DR

This paper investigates how Coulomb interactions in a quantum-dot hybrid nanowire system affect Majorana zero-modes, revealing that interactions can induce wavefunction overlap and trivial bound states, impacting topological protection.

Contribution

It introduces the topological quality factor and shows how Coulomb interactions cause Majorana wavefunction overlap, affecting topological quantum computing.

Findings

Coulomb interactions induce Majorana wavefunction overlap

Formation of trivial Andreev bound states due to interactions

Interaction reduces the topological protection quality factor

Abstract

We study the low-energy transport properties of a hybrid device composed by a native quantum dot coupled to both ends of a topological superconducting nanowire section hosting Majorana zero-modes. The account of the coupling between the dot and the farthest Majorana zero-mode allows to introduce the topological quality factor, characterizing the level of topological protection in the system. We demonstrate that Coulomb interaction between the dot and the topological superconducting section leads to the onset of the additional overlap of the wavefunctions describing the Majorana zero-modes, leading to the formation of trivial Andreev bound states even for spatially well-separated Majoranas. This leads to the spoiling of the quality factor and introduces a constraint for the braiding process required to perform topological quantum computing operations.