Particle-hole bound states of dipolar molecules in optical lattice

TL;DR

This paper studies how dipolar molecules in optical lattices form particle-hole bound states due to strong dipole interactions, analyzing their properties, symmetries, and potential experimental observation.

Contribution

It provides a detailed analysis of particle-hole bound states in dipolar molecules within an extended Bose-Hubbard model, including their spectra, symmetries, and dependence on interaction strength.

Findings

Bound states form in strong dipole interactions in 1D and 2D.

Bound state energies increase and merge into continuum as interaction weakens.

Number and distribution of bound states vary with momentum.

Abstract

We investigate the particle-hole pair excitations of dipolar molecules in optical lattice, which can be described with an extended Bose-Hubbard model. For strong enough dipole-dipole interaction, the particle-hole pair excitations can form bound states in one and two dimensions. With decreasing dipole-dipole interaction, the energies of the bound states increase and merge into the particle-hole continuous spectrum gradually. The existence regions, the energy spectra and the wave functions of the bound states are carefully studied and the symmetries of the bound states are analyzed with group theory. For a given dipole-dipole interaction, the number of bound states varies in momentum space and a number distribution of the bound states is illustrated. We also discuss how to observe these bound states in future experiments.