Three-dimensional higher-order topological insulators can have topologically protected chiral modes propagating on their hinges. Hinges with two co-propagating chiral modes can serve as a "beam splitter" between hinges with only a single chiral mode. Here we show how such a crystal, with Ohmic contacts attached to its hinges, can be used to realize a Mach-Zehnder interferometer. We present concrete calculations for a lattice model of a first-order topological insulator in a magnetic field, which, for a suitable choice of parameters, is an extrinsic second-order topological insulator with the required configuration of chiral hinge modes.
@article{arxiv.2210.02749,
title = {Hinge States of Second-Order Topological Insulators as a Mach-Zehnder Interferometer},
author = {Adam Yanis Chaou and Piet W. Brouwer and Nicholas Sedlmayr},
journal= {arXiv preprint arXiv:2210.02749},
year = {2023}
}