Quantum phases of strongly-interacting bosons on a two-leg Haldane ladder

TL;DR

This paper explores the rich ground-state phases of strongly interacting bosons on a two-leg Haldane ladder, revealing novel vortex-lattice phases and phase distinctions via current and momentum measurements.

Contribution

It introduces the emergence of an unconventional vortex-lattice phase in strongly interacting bosons on a Haldane ladder, supported by analytical and numerical analysis.

Findings

Multiple Meissner-like and vortex-fluid phases identified.

Unconventional vortex-lattice phase stable even for hardcore bosons.

Phase distinctions observable through chiral current and momentum distribution measurements.

Abstract

We study the ground-state physics of a single-component Haldane model on a hexagonal two-leg ladder geometry with a particular focus on strongly interacting bosonic particles. We concentrate our analysis on the regime of less than one particle per unit-cell. As a main result, we observe several Meissner-like and vortex-fluid phases both for a superfluid as well as a Mott-insulating background. Furthermore, we show that for strongly interacting bosonic particles an unconventional vortex-lattice phase emerges, which is stable even in the regime of hardcore bosons. We discuss the mechanism for its stabilization for finite interactions by a means of an analytical approximation. We show how the different phases may be discerned by measuring the nearest- and next-nearest-neighbor chiral currents as well as their characteristic momentum distributions.