Topological superconductivity induced by proximity effects

Abstract

A fundamental obstacle for achieving quantum computation is the local decoherence. One way to solve this problem is based on the concepts of topological quantum computation assuming a condensed-matter realization of Majorana fermions (MF). MF are expected to occur in p-wave superconductors. However, p-wave topological superconductors have not been discovered yet. One of the alternative theoretical proposals is the occurrence of topological superconductivity in conventional s-wave superconductor - semimetal junctions, when the semimetal possesses a certain form of the spin-orbit coupling. In this project, we are planning to realize the experimental study of possible topological superconductivity in the proximity coupled Nb (s-wave superconductor) - Bi (semimetal with a strong spin-orbit coupling) composites. Besides of the MF, another class of topological systems is given by bound states of Jackiw-Rebbi (JR) type containing fractional charge e/2. Similar to MF, such quantum states offer the possibility for applications in quantum computation, when they exhibit non-Abelian statistics. Recently, it has been theoretically demonstrated the occurrence of JR solitons at the interface between conventional superconductor and quantum-disordered frustrated antiferromagnets (AFM), including quantum spin liquids. Our proposal is to experimentally explore the possible occurrence of JR solitons at the interfaces between Nb and CuO, antiferromagnetic with a controllable disorder strength. (AU)