Instabilities and the roton spectrum of a quasi-1D Bose-Einstein condensed gas with dipole-dipole interactions

Abstract

We point out the possibility of having a roton-type excitation spectrum in a quasi-1D Bose-Einstein condensate with dipole-dipole interactions. Normally such a system is quite unstable due to the attractive portion of the dipolar interaction. However, by reversing the sign of the dipolar interaction using either a rotating magnetic field or a laser with circular polarization, a stable cigar-shaped configuration can be achieved whose spectrum contains a `roton' minimum analogous to that found in helium II. Dipolar gases also offer the exciting prospect to tune the depth of this `roton' minimum by directly controlling the interparticle interaction strength. When the minimum touches the zero-energy axis the system is once again unstable, possibly to the formation of a density wave.

7 pages, 6 figures. Special Issue: "Ultracold Polar Molecules: Formation and Collisions"

References in corpus (1)

• Exact hydrodynamics of a trapped dipolar Bose-Einstein condensate

Cited by in corpus (8)

• Stability of quasi-two-dimensional Bose-Einstein condensates with dominant dipole-dipole interactions
• Dipolar gases in quasi one-dimensional geometries
• Evidence of Luttinger liquid behavior in one-dimensional dipolar quantum gases
• Stability of dark solitons in three dimensional dipolar Bose-Einstein condensates
• Structure formation during the collapse of a dipolar atomic Bose-Einstein condensate
• Ground-state structure and stability of dipolar condensates in anisotropic traps
• Vortex in a trapped Bose-Einstein condensate with dipole-dipole interactions
• Collective oscillations of dipolar Bose-Einstein condensates and accurate comparison between contact and dipolar interaction