Spinful bosons in an optical lattice

TL;DR

This paper investigates the phases of spin-1 bosons in a one-dimensional optical lattice, revealing a phase diagram with Mott insulators and superfluid states, using advanced numerical methods.

Contribution

It provides the first detailed phase diagram for spin-1 bosons in optical lattices, confirming theoretical predictions and exploring the effects of large spin interactions.

Findings

Confirmation of the phase diagram with Mott-insulating and dimerized phases.

Identification of on-site singlet dominance at large spin interactions.

No evidence of additional ordered phases in accessible regions.

Abstract

We analyze the behavior of cold spin-1 particles with antiferromagnetic interactions in a one-dimensional optical lattice using density matrix renormalization group calculations. Correlation functions and the dimerization are shown and we also present results for the energy gap between ground state and the spin excited states. We confirm the anticipated phase diagram, with Mott-insulating regions of alternating dimerized S=1 chains for odd particle density versus on-site singlets for even density. We find no evidence for any additional ordered phases in the physically accessible region, however for sufficiently large spin interaction, on-site singlet pairs dominate leading, for odd density, to a breakdown of the Mott insulator or, for even density, a real-space singlet superfluid.