Majorana mode leaking into a spin-charge entangled double quantum dot

TL;DR

This paper theoretically investigates how Majorana zero-energy modes influence a spin-charge entangled double quantum dot system, revealing unique spectral features and conductance modifications in the strong correlation regime.

Contribution

It demonstrates the impact of Majorana modes on local density of states and conductance in a double quantum dot setup, including effects of finite wire length and mode overlap.

Findings

Majorana modes induce unique features in the local density of states.

Presence of Majorana modes modifies the gate voltage dependence of conductance.

Finite wire length and mode overlap affect local spectral properties.

Abstract

The signatures of Majorana zero-energy mode leaking into a spin-charge entangled double quantum dot are investigated theoretically in the strong electron correlation regime. The considered setup consists of two capacitively coupled quantum dots attached to external contacts and side-attached to topological superconducting wire hosting Majorana quasiparticles. We show that the presence of Majorana mode gives rise to unique features in the local density of states in the $SU(4)$ Kondo regime. Moreover, it greatly modifies the gate voltage dependence of the linear conductance, leading to fractional values of the conductance. We also analyze the effect of a finite length of topological wire and demonstrate that non-zero overlap of Majorana modes at the ends of the wire is revealed in local extrema present in the local density of states of the dot coupled directly to the wire. The calculations are performed with the aid of the numerical renormalization group method.