Effect of Abrikosov vortices on the superconducting quantum interference pattern of topological insulator Josephson junction

Josephson junctions based on hybrid structures between topological insulators and superconductors are a promising platform for fault-tolerant quantum computing. The superconducting quantum interference (SQI) pattern in these Josephson junctions can encode information about the nature of superconductivity. Here, we show that the measured SQI patterns obtained from Josephson junctions fabricated based on cadmium arsenide thin films, which is a two-dimensional topological insulator, deviate from an ideal Fraunhofer pattern. We use a theoretical model that accounts for Abrikosov (anti-) vortices in the superconducting contacts to describe many of these observed anomalies, such as node-lifting, anomalous phase shifts, even/odd effects, irregular lobe spacing, and an asymmetry in magnetic field. We also show that these vortices can enter the contacts under current bias even with no intentional magnetic field applied. Finally, we present cadmium arsenide Josephson junctions that are constructed with narrow superconducting strips where vortices are fully expelled and ideal Fraunhofer patterns are observed. This work demonstrates that topological superconductivity does not need to be inferred to fully explain the commonly seen anomalies in topological insulator Josephson junctions.