Correlating parity transitions with zero-bias peaks in hybrid semiconducting-superconducting nanowires.

Semiconducting nanowires covered by superconducting shells have been intensively investigated for almost a decade due to their potential to host non-abelian topological excitations - Majorana zero modes (MZMs) [1, 2, 3, 4]. To date, two methods have been primarily used for their identification: tunneling and Coulomb spectroscopy. Here we present an experimental protocol that allows to perform both types of spectroscopy measurements on the same device. We demonstrate that despite the absence of zero-bias peaks in tunneling spectroscopy, 2e-1e parity transitions in island experiments can be observed. Our results emphasize the need of combined measurements in order to unambiguously demonstrate the existence of MZMs.

[1] Mourik, V. et al. Signatures of Majorana Fermions in Hybrid Superconductor-Semiconductor Nanowire Devices. Science 336, 1003–1007 (2012)

[2] Albrecht, S. M. et al. Exponential protection of zero modes in Majorana islands. Nature 531, 206–209 (2016).

[3] Vaitiekenas, S. et al. Flux-induced topological superconductivity in full-shell nanowires. Science 367, eaav3392 (2020).

[4] Valentini, M. et al. Nontopological zero-bias  peaks in full-shell nanowires induced by flux-tunable andreev states. Science 373, 82–88 (2021).