Barriers to macroscopic superfluidity and insulation in a 2D Aubry–André model

Abstract

We study the ground state phases of interacting bosons in the presence of a 2D Aubry-André potential. By using a a mean-field percolation analysis, we focus on several superlattice and quasicrystalline regimes of the 2D Aubry-André model, including generalisations that account for a tilting or skewing of the potential. We show that barriers to the onset of macroscopic phases naturally arise from weakly modulated domains in the 2D Aubry-André model. This leads to the formation of extended crossover domains, in which the macroscopic properties are dominated by a minority of the system. The phase diagrams then exhibit substantially different features when compared against crystalline systems, including a lobe-like or wave-like appearance of the Bose glass, sharp extrusions and thin, percolating clusters. By studying the 2D Aubry-André model across multiple regimes, we have shown that these extended crossover domains are not distinct to a small set of parameters.