Observation of spin-orbit coupling induced Weyl points and topologically protected Kondo effect in a two-electron double quantum dot

TL;DR

This paper demonstrates the experimental and theoretical discovery of Weyl points in an interacting quantum dot system, revealing topologically protected degeneracies and a Kondo effect robust against spin-orbit coupling.

Contribution

It shows that Weyl degeneracies can naturally occur in quantum dots under magnetic fields, extending topological concepts to interacting nanoscale systems.

Findings

Weyl points observed in InAs double quantum dot

Robust topologically protected Kondo effect detected

Weyl degeneracies persist despite spin-orbit coupling

Abstract

Recent years have brought an explosion of activities in the research of topological aspects of condensed-matter systems. Topologically non-trivial phases of matter are typically accompanied by protected surface states or exotic degenerate excitations such as Majorana end states or Haldane's localized spinons. Topologically protected degeneracies can, however, also appear in the bulk. An intriguing example is provided by Weyl semimetals, where topologically protected electronic band degeneracies and exotic surface states emerge even in the absence of interactions. Here we demonstrate experimentally and theoretically that Weyl degeneracies appear naturally in an interacting quantum dot system, for specific values of the external magnetic field. These magnetic Weyl points are robust against spin-orbit coupling unavoidably present in most quantum dot devices. Our transport experiments through an InAs double dot device placed in magnetic field reveal the presence of a pair of Weyl points, exhibiting a robust ground state degeneracy and a corresponding protected Kondo effect.