A team proposes topological Josephson trijunctions, three-arm superconducting junctions on a semiconductor nanowire, as a platform to generate and steer Majorana quasiparticles. The three-way geometry would allow a pair of Majoranas to be created at a branching point and the supercurrent to travel along distinct paths, something two-terminal junctions cannot achieve.

The idea builds on the physics of Majorana modes that appear at superconductor-semiconductor interfaces with spin-orbit coupling and a magnetic field. In a trijunction, each arm hosts a Majorana mode at its end, and the central region acts as a node where the quantum amplitudes of the states are distributed. This turns the Josephson network into a Majorana interferometer, where the superconducting phase accumulated in each branch controls the interference.

The work analyzes how the Josephson current through the node depends on the phase differences between the three arms and on the coupling energy between the Majorana modes. The authors describe signatures of the Majorana nature of the states in the dependence of the current on phase and magnetic field, and propose transport measurements that would distinguish these modes from ordinary Andreev states.

The relevance lies in that a trijunction could serve both as a source of Majorana pairs and as a control element to move them between branches, a step toward manipulating topological information. The proposal connects with ongoing efforts to build topological qubits based on networks of superconducting nanowires, where topology protects information against local perturbations. Experimental implementation and verification of the predicted signatures in real samples remain pending.