Quantum Josephson junctions in topological insulators show Fraunhofer patterns in a field

Researchers at the University of Cologne and the Chinese Academy of Sciences have demonstrated a multiterminal Josephson effect in side-contacted topological insulator trijunctions, revealing key features of superconducting current flow. The work establishes experimental evidence for two-dimensional critical current contours and identifies bias regimes where current isolates to a single junction within the trijunction. Magnetic fields applied to these junctions produce Fraunhofer patterns and SQUID oscillations, reflecting flux buildup within the device loop. These results provide foundations for future investigations into Majorana zero modes, a component in some theoretical approaches to topological quantum computing. Side-contacted topological insulator trijunctions exhibit deformations of their critical current contours when exposed to perpendicular magnetic fields, a phenomenon reflecting flux buildup within…