  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.
