Quantum phase transition of dipolar bosons in optical lattices

In terms of the Green.'s function method we study the energy spectrum of dipolar boson atoms with the dipole-dipole interaction in an optical lattice. The Superfluid-Mott-Insulator phase transition condition of the dipolar bosons is determined from the energy-band structure of the excitation spectrum as a function of interatomic repulsion, dipolar bosons interaction and the tunnel coupling constants. The superfluid phase is explained explicitly from the energy spectrum derived in terms of the Bogoliubov approach as well.