Observation of spin–orbit coupling induced Weyl points in a two-electron double quantum dot.

Recent years have brought an explosion of activities in the research of topological aspects of condensed-matter systems. Topological phases of matter are accompanied by protected surface states or exotic degenerate excitations such as Majorana modes 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. Weyl semimetals are a class of crystalline materials whose electronic band structure exhibits topologically protected degeneracy points, known as Weyl points. Here, the authors demonstrate both theoretically and experimentally that Weyl points can also be present in the magnetic-field dependent spectrum of a double quantum dot system, enjoying a similar topological protection. [ABSTRACT FROM AUTHOR]