Dipolar bosons on an optical lattice ring
  We consider an ultra-small system of polarized bosons on an optical lattice with a ring topology interacting via long range dipole-dipole interactions. Dipoles polarized perpendicular to the plane of the ring reveal sharp transitions between different density wave phases. As the strength of the dipolar interactions is varied the behavior of the transitions is first-order like. For dipoles polarized in the plane of the ring the transitions between possible phases show pronounced sensitivity to the lattice depth. The abundance of possible configurations may be useful for quantum information applications. 
Michal Maik, Pierfrancesco Buonsante, Alessandro Vezzani and Jakub   Zakrzewski
cond-mat.quant-gas quant-ph