title: Roton-maxon spectrum and stability of trapped dipolar Bose-Einstein condensates.
abstract: We find that pancake dipolar condensates can exhibit a roton-maxon character of the excitation spectrum, so far observed only in superfluid helium. We also obtain a condition for the dynamical stability of these condensates. The spectrum and the border of instability are tunable by varying the particle density and/or the confining potential. This opens wide possibilities for manipulating the superfluid properties of dipolar condensates.
authors.affiliation: Institut für Theoretische Physik, Universität Hannover, D-30167 Hannover, Germany.
authors.forename: L
authors.initials: L
authors.lastname: Santos
authors.forename: G V
authors.initials: GV
authors.lastname: Shlyapnikov
authors.forename: M
authors.initials: M
authors.lastname: Lewenstein