Topological Order in Frustrated Josephson Junction Arrays

TL;DR

This paper demonstrates that frustrated Josephson junction arrays exhibit topological order with unique ground state degeneracy, sharing gauge dynamics with unfrustrated arrays but featuring fractional excitations similar to those in fractional quantum Hall systems.

Contribution

It reveals topological order in frustrated JJAs and introduces fractional degrees of freedom analogous to composite electrons in quantum Hall effects.

Findings

Topological degeneracy in frustrated JJAs

Fractional gauge degrees of freedom identified

Similarity to fractional quantum Hall physics

Abstract

We show that electrically and magnetically frustrated Josephson junction arrays (JJAs) realize topological order with a non-trivial ground state degeneracy on manifolds with non-trivial topology. The low-energy theory has the same gauge dynamics of the unfrustrated JJAs but for different, "fractional" degrees of freedom, a principle reminescent of Jain's composite electrons in the fractional quantum Hall effect.