Engineering Kitaev chains in InSb nanowires

The promise of combining quantum information processing with topology, making it intrinsically resistant to local perturbations, has driven over two decades of both theoretical and experimental research. Spatially separated Majorana Zero Modes (MZM) are predicted to appear at the ends of 1D nanostructures obtained by interfacing high spin-orbit coupling semiconductors with metallic superconductors. However, signatures of topological behaviors have always been elusive, and no clear demonstration of non-Abelian properties has been reported so far. Many problems disrupting the formation and detection of the topological phase originate from a lack of control over the microscopic details of the electron potential landscape in those heterostructure devices. In recent years Dvir et al. demonstrated the possibility of engineering Kitaev chains in InSb nanowires with a bottom-up approach, coupling an array of quantum dots via short superconducting segments. Each component of the system can be carefully controlled via gating potential to overcome the challenges given by random disorder. At fine-tuned sweet spots, Majorana states appear at the end of the chain. Although not topologically protected (due to the finite number of sites in the chain) these excitations are predicted to share their non-Abelian nature with their topological counterparts and to become more and more resistant to noise as the number of sites increases.

In this talk, I will present the principles at the basis of this approach and the most recent experimental developments.