Proposal for the detection and braiding of Majorana fermions in a quantum spin Hall insulator

We show how a quantum dot with a ballistic single-channel point contact to a superconductor can be created by means of a gate electrode at the edge of a quantum spin Hall insulator (such as an InAs/GaSb quantum well). A weak perpendicular magnetic field traps a Majorana zero mode, so that it can be observed in the gate-voltage-averaged differential conductance $\langle dI/dV\rangle$ as a $4e^2/h$ zero-bias peak above a $(\frac{2}{3}{\pi }^2-4)e^2/h$ background. The one-dimensional edge does not permit the braiding of pairs of Majorana fermions, but this obstacle can be overcome by coupling opposite edges at a constriction, allowing for a demonstration of non-Abelian statistics. DOI: http://dx.doi.org/10.1103/PhysRevB.87.241405 ©2013 American Physical Society