Topological phase detection in Rashba nanowires

Par Denis Chevallier, Université de Bâle, Suisse

Mardi 19 Juin, 14h00, Salle des séminaires (215), 2ème étage, Bâtiment A4N

Abstract :

We study the detection of the topological phase transition occurring in Rashba/Majorana nanowires with proximity-induced superconductivity using a quantum dot. The lowest in energy bulk states of such a nanowire have a spin polarization parallel or antiparallel to the applied magnetic field in the topological or trivial phase. We show that this property can be probed by the quantum dot created at the end of the nanowire by external gates. By tuning one of the two spin-split levels of the quantum dot to be in resonance with nanowire bulk states, one can detect the spin polarization of the lowest band via transport measurement. Thus, this allows us to determine the topological phase of the Rashba nanowire independently of the presence of the zero-energy Majorana bound states. Our work opens an entirely new path for experimental approaches to detect topological superconductivity. Our results demonstrate the feasibility of such measurements in realistic setups and thus provide a strong incentive for experimental implementations for many labs worldwide. Such experiments would be highly welcome by the community as they can provide independent support of topological phases, and in this way help to resolve the controversy surrounding the interpretation of zero-bias peaks as Majorana bound states.