SPT 2-Channel Kondo Model in the Structure of Normal Metal/Quantum Dot/DIII-class Topological Superconductor

TL;DR

This paper explores the Kondo effect in a hybrid structure with a quantum dot coupled to a normal metal and a DIII-class topological superconductor, revealing topologically protected Kondo correlations and multiple Kondo temperature regimes influenced by Majorana doublets.

Contribution

It introduces a topologically protected Kondo model involving Majorana doublets and demonstrates multiple Kondo temperature regimes due to coupling variations.

Findings

Kondo correlation involves both metal and Andreev reflection states.

Kondo model Hamiltonian is protected by specific symmetries.

Kondo temperature exhibits three distinct forms depending on coupling strength.

Abstract

We investigate the Kondo effect in a structure which is constructed by embedding one quantum dot between a normal metal and a \emph{DIII}-class topological superconductor supporting Majorana doublets at its ends. It is observed that Kondo correlation occurs between the localized state in the dot and two continuum states simultaneously, i.e., the continuum state in the metal and the continuum Andreev reflection state between the metal and topological superconductor. As a result, the Kondo model Hamiltonian is topologically protected by the $SU(2)_s\rtimes Z_2^T$ symmetry. Besides, the Kondo temperature has an opportunity to present three forms in turn, following the enhancement of the coupling between the dot and Majorana doublet. This phenomenon exactly reflects the special role of Majorana doublet in tuning the Kondo effect.