Josephson junction arrays as a platform for topological phases of matter

TL;DR

This paper proposes and analyzes two-dimensional superconductor-normal metal arrays as tunable platforms for realizing and detecting chiral topological superconductivity, with clear experimental signatures and controllable parameters.

Contribution

It introduces minimal models for chiral topological phases in superconductor-semiconductor heterostructures and demonstrates their tunability and experimental signatures.

Findings

Topological transitions can be controlled via phase, flux, or exchange field.

Transport signatures uniquely indicate chiral topological phases.

Platforms are highly flexible and suitable for experimental exploration.

Abstract

Two-dimensional arrays of superconductors separated by normal metallic regions exhibit rich phenomenology and a high degree of controllability. We establish such systems as platforms for topological phases of matter, and in particular chiral topological superconductivity. We propose and theoretically analyze several minimal models for this chiral phase based on commonly available superconductor-semiconductor heterostructures. The topological transitions can be adjusted using a time-reversal-symmetry breaking knob, which can be activated by controlling the phases in the islands, introducing flux through the system, or applying an in-plane exchange field. We demonstrate transport signatures of the chiral topological phase that are unlikely to be mimicked by local non-topological effects. The flexibility and tunability of our platforms, along with the clear-cut experimental fingerprints, make for a viable playground for exploring chiral superconductivity in two dimensions.