title: Observation of harmonic generation and nonlinear coupling in the collective dynamics of a bose-einstein condensate
abstract: We report the observation of harmonic generation and strong nonlinear coupling of two collective modes of a condensed gas of rubidium atoms. Using a modified time averaged orbiting potential trap we changed the trap anisotropy to a value where the frequency of the m = 0 high-lying mode corresponds to twice the frequency of the m = 0 low-lying mode, thus leading to strong nonlinear coupling between these modes. By changing the anisotropy of the trap and exciting the low-lying mode we observed significant frequency shifts of this fundamental mode and also the generation of its second harmonic.
authors.affiliation: Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford, OX1 3PU, United Kingdom.
authors.initials: G
authors.lastname: Hechenblaikner
authors.initials: OM
authors.lastname: Marago
authors.initials: E
authors.lastname: Hodby
authors.initials: J
authors.lastname: Arlt
authors.initials: S
authors.lastname: Hopkins
authors.initials: CJ
authors.lastname: Foot