Strongly interacting Majorana modes in an array of Josephson junctions

An array of superconducting islands with semiconducting nanowires in the right regime provides a macroscopic implementation of Kitaev's toy model for Majorana wires. We show that a capacitive coupling between adjacent islands leads to an effective interaction between the Majorana modes. We demonstrate that, even though strong repulsive interaction eventually drives the system into a Mott insulating state, the competition between the (trivial) band insulator and the (trivial) Mott insulator leads to an interjacent topological insulating state for arbitrary strong interactions.