Tunneling transport through superconducting wires with Majorana bound states

We investigate the transport of a topological superconducting wire hosting a pair of Majorana bound states between two normal leads. Both the model-independent scattering matrix theory and the Green's function method for a tight-binding model show that the transport properties are sensitive to the coupling configurations. Unlike the single-lead situation, the differential conductance peak fixes at zero bias until the coupling between the two Majorana bound states exceeds a critical value, which is determined by the coupling strengths to the leads. While the current noise Fano factor for single-lead devices reaches 2 at low bias due to the resonant Andreev reflection, it is significantly reduced by a finite though small coupling to the second lead. These observations provide clear transport signatures of Majorana bound states for different coupling configurations.