Affiliation
Institute of Science and Technology Austria, Austria
Web
Talk Title
Majorana-like Coulomb spectroscopy in the absence of zero bias peaks
Abstract
Hybrid semiconductor-superconductor devices hold great promise for realizing topological superconductivity. To date, claims of Majorana detection, separately using tunneling and Coulomb spectroscopy, remain debated. In order to remove interpretation ambiguities we devise an experimental protocol that allows to perform both types of measurement on the same device. Our results show that uniformly spaced single electron Coulomb-blockade conductance peaks can be observed even in the absence of zero bias peaks. Furthermore, we demonstrate that the single electron Coulomb peak spacing oscillations, often interpreted as the result of overlapping Majorana bound states, strongly depend on the tunnel junction transparencies of the superconducting island, which rules out topological edge states. We interpret them instead as the result of longitudinal confinement in the superconducting island. Our results highlight the necessity of combined measurements in order to gain a deeper understanding of hybrid devices and demonstrate the existence of topological Majorana zero modes.