Advanced hybrid InSb/Al nanowires devices for topological parity readout (Part 1)*

Majorana bound states (MBS) in hybrid semi-superconducting systems have been proposed to be the building blocks of the next quantum computers. Quantum information can be stored in the fermionic parity degree of freedom, shared in two well-separated MBS. A promising method to readout such parity is to measure the conductance through an Aharonov-Bohm (AB) interferometer, hosting a pair of MBS in one of the interfering arms. Here, we report our progress in the realization of such device based on InSb/Al islands. We first investigate the electron-phase evolution in a normal quantum dot embedded in an InSb nanowire network by mapping the phase of AB oscillations. Phase lapse and winding are extracted from the shift of these oscillations and from the associated Fano effect. Secondly, we study the energy spectrum of proximitized InSb nanowires in Coulomb blockade revealing gate-dependent ground state parity transitions as a function of magnetic field. Based on these results and on the development of a new nanofabrication technique, interferometric readout can be performed in both nano-networks and single-nanowire architectures.