Majorana Bound States in the Diffraction Patterns of S-TI-S Lateral Josephson Junctions

In an extended superconductor-topological insulator-superconductor (S-TI-S) Josephson junction, localized Majorana bound states (MBS) are predicted to exist where the local phase difference across the junction is an odd-multiple of π. These states can induce a supercurrent with a 4π-periodic current-phase relation (CPR). In this talk, we present an extensive study of the critical current vs. magnetic field diffraction patterns of S-TI-S lateral Josephson junction devices, comparing measurements and simulations. The measurement exhibits distinct deviations from the usual Fraunhofer diffraction pattern of uniform extended Josephson junctions which include the lifting of odd-numbered nodes, features that signify the entry of Majorana states, and evidence for parity states and fluctuations. We compare results from junctions with TI barriers of Bi₂Se₃ and Bi_0.8Sb_1.2Te₃ and non-TI graphene barriers.