Novel scenarios in dipolar Bose-Einstein condensates

Abstract

Recent years have witness a rapidly growing interest on dipolar gases, which differ significantly from their non-dipolar counterparts due to the anisotropic long-range character of the dipole-dipole interaction. Within this project we will explore the novel physics of trapped dipolar Bose-Einstein condensates, focusing on realistic scenarios, in particular in the context of on-going experiments with ultra-cold magnetic atoms. We will focus on three topics in which the physics of dipolar gases significantly differ qualitatively from that of non-dipolar ones. A first topic concerns one of the most novel features of dipolar condensates, the expected roton-like character of the dispersion of elementary excitations. We will explore in close contact with experimental groups the best scenarios for the, up to now elusive, observation of the roton-like minimum. We will analyze as well the physics associated to roton confinement, and how it affects roton instability in trapped condensates with a superimposed one-dimensional optical lattice. A second idea deals with two-dimensional solitons, a remarkable novel nonlinear feature of dipolar condensates. We will study in particular the best scenarios for the observation of two-dimensional solitons in realistic experiments, and analyze the stability and scatting properties of inter-site soliton dimers in one-dimensional optical lattices. A third research proposal deals with the physics of mixtures of dipolar bosons and dipolar fermions, an interesting novel scenario opened by recent experiments in which different isotopes of a dipolar species may be simultaneously trapped. We will focus in particular on the stability properties of the mixture, the possibility of anisotropic phase separation, and the effects of the dipolar condensate on the Fermi surface deformation of the dipolar gas. (AU)