Robust Fabry-Perot interference in dual-gated Bi$_2$Se$_3$ devices

摘要

We study Fabry-Perot interference in hybrid devices, each consisting of amesoscopic superconducting disk deposited on the surface of a three-dimensionaltopological insulator. Such structures are hypothesized to contain protectedzero modes known as Majorana fermions bound to vortices. The interferencemanifests as periodic conductance oscillations of magnitude $\sim 0.1$ $e^2/h$.These oscillations show no strong dependence on bulk carrier density or samplethickness, suggesting that they result from phase coherent transport in surfacestates. However, the Fabry-Perot interference can be tuned by both top and backgates, implying strong electrostatic coupling between the top and bottomsurfaces of topological insulator.