Detecting Topological Superconductivity with $\varphi_{0}$ Josephson Junctions
Abstract
The interplay of superconductivity, magnetic fields, and spin-orbit interaction lies at the heart of topological superconductivity. Remarkably, the recent experimental discovery of Josephson junctions by Szombati et al., Nat. Phys. 12, 568 (2016), characterized by a finite phase offset in the supercurrent, require the same ingredients as topological superconductors, which suggests a profound connection between these two distinct phenomena. Here, we theoretically show that a quantum dot Josephson junction can serve as a new qualitative indicator for topological superconductivity: Microscopically, we find that the phase shift in a junction of wave superconductors is due to the spin-orbit induced mixing of singly occupied states on the qantum dot, while for a topological superconductor junction it is due to singlet-triplet mixing. Because of this important difference, when the spin-orbit vector of the quantum dot and the external Zeeman field are orthogonal, the -wave superconductors form a Josephson junction while the topological superconductors have a finite offset by which topological superconductivity can be distinguished from conventional superconductivity. Our prediction can be immediately tested in nanowire systems currently used for Majorana fermion experiments and thus offers a new and realistic approach for detecting topological bound states.
Cite
@article{arxiv.1607.07794,
title = {Detecting Topological Superconductivity with $\varphi_{0}$ Josephson Junctions},
author = {Constantin Schrade and Silas Hoffman and Daniel Loss},
journal= {arXiv preprint arXiv:1607.07794},
year = {2017}
}