Dimer states in atomic mixtures

TL;DR

This paper investigates the formation of dimer states in a mixture of heavy and light atoms in an optical lattice, deriving an effective Hamiltonian to describe various low-energy states including Ne9el, dimer, and density wave states.

Contribution

It introduces an effective Hamiltonian for atomic mixtures in optical lattices, capturing the emergence of dimer states and other phases due to inelastic scattering effects.

Findings

Identification of dimer states at moderate interactions

Derivation of an effective Hamiltonian including tunneling and spin exchange

Prediction of Ne9el, dimer, and density wave phases

Abstract

A mixture of heavy atoms in a Mott state and light spin-1/2 fermionic atoms is studied in an optical lattice. Inelastic scattering processes between both atomic species excite the heavy atoms and renormalize the tunneling rate as well as the interaction of the light atoms. An effective Hamiltonian for the latter is derived that describes tunneling of single fermions, tunneling of fermionic pairs and an exchange of fermionic spins. Low energy states of this Hamiltonian are a N\'eel state for strong effective repulsion, dimer states for moderate interaction, and a density wave of paired fermions for strong effective attraction.