Detecting the topological winding of superconducting nodes via local density of states

The authors propose here a method to use impurity scattering to detect interference effects between two superconducting nodes, each of which carries locally a winding number as a topological invariant. Steps are outlined for choosing an impurity and a tip for the scanning tunnelling microscope, such that the winding difference of the nodes becomes measurable via the local density of states around the impurity. The formalism is demonstrated on a model of a two-dimensional superconductor, but applies to any nodal system with chiral symmetry.