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 <dI/dV> as a 4e²/ h zero-bias peak above a (2/3π² - 4)e²/ 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. [ABSTRACT FROM AUTHOR]