Elementary and topological excitations in ultracold dipolar Bose gases

Youssef Kora, Massimo Boninsegni

Adam Griffin

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Francesca Ferlaino

Maciej Lewenstein, Anna Sanpera, V. Ahufinger

This chapter examines ultracold dipolar gases. First, it discusses the general properties of dipole–dipole interaction and explains how ultracold dipolar systems can be realized in experiments. The chapter reviews the properties of ultracold trapped dipolar Bose gases, pointing out the appearance of the roton minimum in the excitation spectrum. It then moves on to dipolar gases in a lattice, and investigates the corresponding extended Hubbard models. Dipolar bosons in a 2D optical lattice are discussed within the Gutzwiller approximation in more detail, with an emphasis on the appearance of multiple metastable states. Next, the chapter considers quantum Monte Carlo studies of dipolar gases, and discusses some further dipolar effects, which can be realized with cold atoms.

Krzysztof Góral, Luis Santos

We analyze the ground-state properties and the excitation spectrum of Bose-Einstein condensates of trapped dipolar particles. First, we consider the case of a single-component polarized dipolar gas. For this case we discuss the influence of the trapping geometry on the stability of the condensate as well as the effects of the dipole-dipole interaction on the excitation spectrum. We discuss also the ground state and excitations of a gas composed of two antiparallel dipolar components.