Topological SQUIPT Based on Helical Edge States in Proximity to Superconductors

We propose a device based on a topological Josephson junction where the helical edge states of a two-dimensional (2D) topological insulator are in close proximity to two superconducting leads. The presence of a magnetic flux through the junction leads to a Doppler shift in the spectrum of Andreev bound states, and affects the quantum interference between proximized edge states. We inspect the emergent features, accessing the density of states through a tunnel-coupled metallic probe, thus realizing a topological superconducting quantum-interference-proximity transistor (TSQUIPT). We calculate the expected performance of this device, concluding that it can be used as a sensitive absolute magnetometer due to the voltage drop across the junction decaying to a constant value as a function of the magnetic flux. Contrary to conventional SQUID and SQUIPT designs, no ring structure is needed. The findings pave the way for sensitive hybrid devices that exploit the helical edge states of a 2D topological insulator.