Chiral Bosonic Phases on the Haldane Honeycomb Lattice

TL;DR

This paper explores the phase diagram of bosons on the Haldane honeycomb lattice, revealing superfluid, chiral superfluid, and Mott insulator phases, with potential experimental observability in ultracold atom systems.

Contribution

It provides the first detailed analysis of chiral bosonic phases on the Haldane lattice, combining numerical and analytical methods to characterize phase transitions and excitations.

Findings

Identified three distinct phases: SF, CSF, and PMI.

Discovered first-order transition between SF and CSF.

Predicted measurable signatures in ultracold atom experiments.

Abstract

Recent experiments in ultracold atoms and photonic analogs have reported the implementation of artificial gauge fields in lattice systems, facilitating the realization of topological phases. Motivated by such advances, we investigate the Haldane honeycomb lattice tight-binding model, for bosons with local interactions at the average filling of one boson per site. We analyze the ground state phase diagram and uncover three distinct phases: a uniform superfluid (SF), a chiral superfluid (CSF) and a plaquette Mott insulator with local current loops (PMI). Nearest-neighbor and next-nearest neighbor currents distinguish CSF from SF, and the phase transition between them is first order. We apply bosonic dynamical mean field theory and exact diagonalization to obtain the phase diagram, complementing numerics with calculations of excitation spectra in strong and weak coupling perturbation theory. The characteristic density fluctuations, current correlation functions, and excitation spectra are measurable in ultracold atom experiments.