• 20.10.2023 - G. Katsaros (P7): Have Majorana zero modes been observed in superconductor-semiconductor devices?

    Seminar talk at Atominstitut, TU Wien

    Hybrid semiconductor–superconductor devices hold great promise for realizing Majorana zero modes [1-3]. However, multiple claims of Majorana detection, based on either tunnelling or Coulomb blockade (CB) spectroscopy, remain disputed. In this talk I will introduce an experimental protocol that allows to perform both types of measurement on the same hybrid island by adjusting its charging energy via tunable junctions to the normal leads [4,5]. This method reduces ambiguities of Majorana detections by checking the consistency between CB spectroscopy and zero-bias peaks in non-blockaded transport. I will discuss the theoretical interpretation of the experimental observations in terms of low-energy, longitudinally confined island states rather than overlapping Majorana modes. The results highlight the importance of combined measurements on the same device for the identification of topological Majorana zero modes.

    [1] Beenakker, C., Annu. Rev. of Condens. Matter Phys. 4, 113 (2013)
    [2] Lutchyn, R. M. et al., Nat. Rev. Mater. 3, 52 (2018)
    [3] Prada, E. et al., Nat. Rev. Phys. 2, 575 (2020)
    [4] Valentini, M. et al., Science 373, 82 (2021)
    [5] Valentini M., Borovkov, M. et al., Nature 612, 442 (2022)