Superfluid-Insulator transition of ultracold atoms in an optical lattice in the presence of a synthetic magnetic field

TL;DR

This paper investigates the superfluid-insulator transition of ultracold bosonic atoms in a 2D optical lattice under a synthetic magnetic field, revealing precursor peaks in momentum distribution and developing an effective theory involving multiple interacting boson fields.

Contribution

It introduces a novel effective theory for the transition involving q interacting boson fields and predicts specific experimental signatures in the presence of synthetic magnetic fields.

Findings

q precursor peaks in momentum distribution

Effective theory with q interacting boson fields

Predictions of gapped and gapless collective modes

Abstract

We study the Mott insulator-superfluid transition of ultracold bosonic atoms in a two-dimensional square optical lattice in the presence of a synthetic magnetic field with p/q (p and q being co-prime integers) flux quanta passing through each lattice plaquette. We show that on approach to the transition from the Mott side, the momentum distribution of the bosons exhibits q precursor peaks within the first magnetic Brillouin zone. We also provide an effective theory for the transition and show that it involves q interacting boson fields. We construct, from a mean-field analysis of this effective theory, the superfluid ground states near the transition and compute, for q=2,3, both the gapped and the gapless collective modes of these states. We suggest experiments to test our theory.