Detecting the Exchange Phase of Majorana Bound States in a Corbino Geometry Topological Josephson Junction

A phase from an adiabatic exchange of Majorana bound states (MBS) reveals their exotic anyonic nature. For detecting this exchange phase, we propose an experimental setup consisting of a Corbino-geometry Josephson junction on the surface of a topological insulator, in which two MBS at zero energy can be created and rotated. We find that if a metallic tip is weakly coupled to a point on the junction, the time-averaged differential conductance of the tip-Majorana coupling shows peaks at the tip voltages $eV = pm (alpha - 2pi l) hbar/ T_J$, where $alpha = pi/2$ is the exchange phase of the two circulating MBS, $T_J$ is the half rotation time of MBS, and $l$ an integer. This result constitutes a clear experimental signature of Majorana fermion exchange.