Ultracold dipolar gas in an optical lattice: The fate of metastable states

We study the physics of ultracold dipolar bosons in optical lattices. We show that dipole-dipole interactions lead to the appearance of many insulating metastable states. We study the stability and lifetime of these states using a generalization of the instanton theory. We also investigate possibilities to prepare, control, and manipulate these states using time-dependent superlattice modifications and modulations. We show that the transfer from one metastable configuration to another necessarily occurs via superfluid states, but can be controlled fully at the quantum level. We show how the metastable states can be created in the presence of a trapping potential. Our findings open the way toward applications of the metastable states as quantum memories.