Impurity-induced bound states as a signature of chiral p-wave superconductivity in Pb_1-xSn_xTe

The recent observation of surface superconductivity on the (001) surface of the topological crystalline insulator Pb_1-xSn_xTe is intriguing, but the nature of the superconducting order is yet to be ascertained. In this context, we have recently proposed that a chiral p-wave superconducting order can be realized on the (001) surface of Pb_1-xSn_xTe, in the presence of weak electronic correlations. In this talk, I will discuss impurity-induced subgap bound states as a possible experimental signature of the chiral p-wave order. In particular, I will introduce two parameter regimes: the normal band gap regime where the subgap bound states are smoothly connected to impurity states in semiconductors, and the inverted band gap regime,where they nontrivially depend on the existence of chiral p-wave superconductivity. I will further discuss properties of the analytically obtained bound state wavefunctions that are peculiar to the chiral p-wave order. For a point defect, these include the quasi-localized nature of the bound-state wavefunctions, and an internal SU(2) rotational symmetry of the zero-energy bound states that enables their use as a possible quantum qubit.