Vortex and Meissner phases of strongly-interacting bosons on a two-leg ladder

TL;DR

This paper maps the phase diagram of strongly-interacting bosons on a two-leg ladder with flux, revealing gapless and gapped Meissner and vortex phases, including Mott-insulating states, through advanced simulations and analysis.

Contribution

It provides a comprehensive phase diagram of the strongly-interacting Bose-Hubbard model on a ladder with flux, combining DMRG simulations and bosonization.

Findings

Identification of gapless and gapped Meissner and vortex phases

Discovery of Mott-insulating regimes with gapped states

Calculation of observable signatures like chiral currents and vortex patterns

Abstract

We establish the phase diagram of the strongly-interacting Bose-Hubbard model defined on a two-leg ladder geometry in the presence of a homogeneous flux. Our work is motivated by a recent experiment [Atala et al., Nature Phys. 10, 588 (2014)], which studied the same system, in the complementary regime of weak interactions. Based on extensive density matrix renormalization group simulations and a bosonization analysis, we fully explore the parameter space spanned by filling, inter-leg tunneling, and flux. As a main result, we demonstrate the existence of gapless and gapped Meissner and vortex phases, with the gapped states emerging in Mott-insulating regimes. We calculate experimentally accessible observables such as chiral currents and vortex patterns.