Topology-induced confined superfluidity in inhomogeneous arrays

TL;DR

This paper explores how topological inhomogeneity in arrays like the comb lattice induces confined superfluid regions, revealing new phase behavior in the Bose-Hubbard model at zero temperature.

Contribution

It demonstrates the existence of confined superfluidity caused by topology in inhomogeneous arrays, extending analytical and numerical methods to these systems.

Findings

Confined superfluid regions exist along the comb backbone.

Topological inhomogeneity causes separation of Mott-insulator and superfluid phases.

Results are relevant for systems like coupled Bose condensates and Josephson arrays.

Abstract

We report the first study of the zero-temperature phase diagram of the Bose-Hubbard model on topologically inhomogeneous arrays. We show that the usual Mott-insulator and superfluid domains, in the paradigmatic case of the comb lattice, are separated by regions where the superfluid behaviour of the bosonic system is confined along the comb backbone. The existence of such {\it confined superfluidity}, arising from topological inhomogeneity, is proved by different analytical and numerical techniques which we extend to the case of inhomogeneous arrays. We also discuss the relevance of our results to real system exhibiting macroscopic phase coherence, such as coupled Bose condensates and Josephson arrays.