Multi-flavor bosonic Hubbard models in the first excited Bloch band of an optical lattice

TL;DR

This paper introduces a new way to realize multi-flavor bosonic Hubbard models using ultra cold atoms excited to the first Bloch band in optical lattices, enabling exploration of complex quantum phases.

Contribution

It proposes a novel method to create multi-flavor bosonic Hubbard Hamiltonians via band excitation and provides detailed analysis of their parameters, stability, and phase diagrams.

Findings

Parameters for the Hamiltonians are derived from band structure calculations.

Mean field phase diagrams are constructed for two- and three-flavor systems.

Atoms in the first band have lifetimes much longer than hopping times, enabling quasi-equilibrium states.

Abstract

We propose that by exciting ultra cold atoms from the zeroth to the first Bloch band in an optical lattice, novel multi-flavor bosonic Hubbard Hamiltonians can be realized in a new way. In these systems, each flavor hops in a separate direction and on-site exchange terms allow pairwise conversion between different flavors. Using band structure calculations, we determine the parameters entering these Hamiltonians and derive the mean field ground state phase diagram for two effective Hamiltonians (2D, two-flavors and 3D, three flavors). Further, we estimate the stability of atoms in the first band using second order perturbation theory and find lifetimes that can be considerable (10-100 times) longer than the relevant time scale associated with inter-site hopping dynamics, suggesting that quasi-equilibrium can be achieved in these meta-stable states.