We reveal the existence of a new type of topological Josephson effect involving type II superconductors and three-dimensional topological insulators as tunnel junctions. We predict that vortex lines induce a variant of the Witten effect that is the consequence of the axion electromagnetic response of the topological insulator: at the interface of the junction each flux quantum attains a fractional electrical charge of e/4. As a consequence, if an external magnetic field is applied perpendicular to the junction, the Witten effect induces an AC Josephson effect in absence of any external voltage. We derive a number of further experimental consequences and propose potential setups where these {quantized, flux induced, Witten} effects may be observed.
@article{arxiv.1607.04150,
title = {Josephson currents induced by the Witten effect},
author = {Flavio S. Nogueira and Zohar Nussinov and Jeroen van den Brink},
journal= {arXiv preprint arXiv:1607.04150},
year = {2016}
}
Comments
5 pages, 1 figure. Published version (PRL editor's suggestion)