Abstract:

Quantum dots on the surface of three-dimensional time-reversal invariant topological insulator (TI) are interesting for a number of reasons. First of all because of the robustness of the topological surface state which is protected against disorder by time-reversal symmetry and the bulk band gap; in the simplest case, the surface state is given by a single Dirac cone characterized by spin-momentum locking. Secondly, because the quantum dot is formed on a surface it is readily accessible to local charge and spin probes such as AFM and SQUID or NV centers, respectively. In this talk, I will first discuss how to confine electrons on the surface of a 3D TI, both by means of a ferromagnetic insulator or by proximity-induced superconductivity. In the first part of my talk, I consider a quantum dot formed by magnetic barriers and the effect of electron-electron interactions in this system and how this gives rise to the formation of a spin-polarized Wigner molecule. Finally, I discuss hybrid quantum rings formed by both magnetic and superconducting barriers and how Majorana zero modes can arise in these systems.