Lecturer: Dr. Anna Kesselman
Abstract:
Topological Josephson junctions form a playground for the interplay between topological and conventional degrees of freedom. This behavior can be experimentally probed using recently built Majorana-transmon devices, which combine conventional superconducting qubit technology with semiconductor-superconductor heterostructures that are expected to host Majorana zero modes. We use matrix-product state techniques to model the spectral response of such qubits within an effective low-energy model of spinful fermions in one dimension that includes the effects of Rashba spin-orbit coupling, Zeeman field, superconductivity and charging interactions. We obtain the experimentally relevant signatures of the topological regime, including the appearance of additional spectral lines and characteristic features in the charge dispersion. Going beyond well-known simplified models for such topological junctions, we include the effects of additional Andreev bound states in the junction. We observe that these hybridize with the bosonic charge modes and lead to features in the spectral response that are reminiscent of experimental observations.