Signature of Dispersing 1D Majorana Channels in an Iron-based Superconductor

Majorana fermions can be realized as quasiparticle excitations in a topological superconductor, whose
non-Abelian statistics provide a route to developing robust qubits. In this context, there has been a
recent surge of interest in the iron-based superconductor, FeSe_0.5 Te_0.5. Theoretical calculations have
shown that FeSe_0.5 Te_0.5 may have an inverted band structure which may lead to topological surface
states, which can in turn host Majorana modes under certain conditions in the superconducting phase.
Furthermore, recent STM studies have demonstrated the existence of zero-bias bound states inside
vortex cores which have been interpreted as signatures of Majorana modes. While most recent studies
have focused on Majorana bound states, more generally, akin to elementary particles, Majorana
fermions can propagate and display linear dispersion. These excitations have not yet been directly
observed, and can also be used for quantum information processing. This talk is focused on our recent
work in realizing dispersing Majorana modes. I will describe the conditions under which such states can
be realized in condensed matter systems and what their signatures are. Finally, I will describe our
scanning tunneling experiments of domain walls in the superconductor FeSe_0.45 Te_0.55 , which might
potentially be first realization of dispersing Majorana states in 1D.