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

Authors: Giovanazzi, S.¹; O'Dell, D.²

Source: The European Physical Journal D - Atomic, Molecular and Optical Physics, Volume 31, Number 2, November 2004 , pp. 439-445(7)

Publisher: Springer

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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 of tuning 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.

Document Type: Research article

DOI: http://dx.doi.org/10.1140/epjd/e2004-00146-7

Affiliations: 1: School of Physics & Astronomy, University of St Andrews, KY16 9SS, North Haugh, St Andrews, Scotland, Email: stevbolz@yahoo.it 2: Dept of Physics & Astronomy, University of Sussex, BN1 9QH, Falmer, Brighton, England,

Publication date: 2004-11-01