Patrick Köberle et al 2009 New J. Phys. 11 023017 doi:10.1088/1367-2630/11/2/023017
Patrick Köberle, Holger Cartarius, Tomaž Fabčič, Jörg Main and Günter Wunner
Show affiliationsWe apply a variational technique to solve the time-dependent Gross–Pitaevskii equation for Bose–Einstein condensates in which an additional dipole–dipole interaction between the atoms is present with the goal of modelling the dynamics of such condensates. We show that universal stability thresholds for the collapse of the condensates correspond to bifurcation points where always two stationary solutions of the Gross–Pitaevskii equation disappear in a tangent bifurcation, one dynamically stable and the other unstable. We point out that the thresholds also correspond to 'exceptional points', i.e. branching singularities of the Hamiltonian. We analyse the dynamics of excited condensate wave functions via Poincaré surfaces of section for the condensate parameters and find both regular and chaotic motion, corresponding to (quasi-) periodically oscillating and irregularly fluctuating condensates, respectively. Stable islands are found to persist up to energies well above the saddle point of the mean-field energy, alongside collapsing modes. The results are applicable when the shape of the condensate is axisymmetric.
03.75.Kk Dynamic properties of condensates; collective and hydrodynamic excitations, superfluid flow
05.45.-a Nonlinear dynamics and nonlinear dynamical systems
05.40.-a Fluctuation phenomena, random processes, noise, and Brownian motion
Issue 2 (February 2009)
Received 26 September 2008
Published 9 February 2009
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