A Topological SQUIPT based on helical edge states in proximity to superconductors

TL;DR

This paper introduces a topological SQUIPT device utilizing helical edge states in a topological insulator, enabling sensitive magnetic flux detection without a ring structure, advancing topological quantum interference applications.

Contribution

It proposes a novel topological SQUIPT device based on helical edge states, demonstrating its potential as a highly sensitive, ring-free magnetometer.

Findings

Device can function as an absolute magnetometer

Voltage drop stabilizes with magnetic flux, enabling detection

No ring structure needed for operation

Abstract

We propose a device based on a topological Josephson junction where the helical edge states of a two-dimensional 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 performances of this new 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 novel and sensitive devices based on hybrid devices that exploit helical edge states.