Interference Effect of Majorana Fermions in a Spin-orbit Coupled Superconducting Wire

Two majorana Fermions (MFs) localized at the two ends of the topological superconducting wire can interfere with each other and form the well known $4\pi$ Josephson current. We reveal that the density of states (Dos) for the electron part and the hole part also follow a parity correlated $4\pi$ period oscillation, while the Dos displays a $2\pi$ period oscillation when two trivial states interfere with each other. Thus, the period of Dos oscillation can be used to distinguish the MFs from the trivial localized states. Interestingly, such phenomena can be directly observed in a short superconducting wire controlled by the gate voltage. This largely simplifies the experimental setup. We suggest that the interference effects can be detected through two STM leads or two norm leads.