Equilibrium phases of two-dimensional bosons in quasi-periodic lattices

TL;DR

This study uses Quantum Monte Carlo simulations to map the phase diagram of two-dimensional bosons in quasi-periodic lattices, revealing superfluid, Mott insulator, and Bose glass phases and their transitions under varying interactions and disorder.

Contribution

First detailed quantum Monte Carlo analysis of bosonic phases in 2D quasi-periodic lattices, clarifying phase transitions and contrasting with random disorder behavior.

Findings

Existence of superfluid, Mott insulator, and Bose glass phases.

Disorder strength needed to destroy superfluidity depends on interaction.

No evidence of Mott-glass-like behavior at large interactions.

Abstract

We report on results of Quantum Monte Carlo simulations for bosons in a two dimensional quasi-periodic optical lattice. We study the ground state phase diagram at unity filling and confirm the existence of three phases: superfluid, Mott insulator, and Bose glass. At lower interaction strength, we find that sizable disorder strength is needed in order to destroy superfluidity in favor of the Bose glass. On the other hand, at large enough interaction superfluidity is completely destroyed in favor of the Mott insulator (at lower disorder strength) or the Bose glass (at larger disorder strength). At intermediate interactions, the system undergoes an insulator to superfluid transition upon increasing the disorder, while a further increase of disorder strength drives the superfluid to Bose glass phase transition. While we are not able to discern between the Mott insulator and the Bose glass at intermediate interactions, we study the transition between these two phases at larger interaction strength and, unlike what reported in arXiv:1110.3213v3 for random disorder, find no evidence of a Mott-glass-like behavior.