Superfluid toroidal currents in atomic condensates

Abstract

The dynamics of toroidal condensates in the presence of condensate flow and dipole perturbation have been investigated. The Bogoliubov spectrum of condensate is calculated for an oblate torus using a discrete-variable representation and a spectral method to high accuracy. The transition from spheroidal to toroidal geometry of the trap displaces the energy levels into narrow bands. The lowest-order acoustic modes are quantized with the dispersion relation $\omega \sim |m|{\omega }_s$ with $m=0,\pm 1,\pm 2,...$. A condensate with toroidal current $\kappa$ splits the $|m|$ co-rotating and counter-rotating pair by the amount: $\Delta E\approx 2|m|{\hslash }^2\kappa <r^{-2}>$. Radial dipole excitations are the lowest energy dissipation modes. For highly occupied condensates the nonlinearity creates an asymmetric mix of dipole circulation and nonlinear shifts in the spectrum of excitations so that the center of mass circulates around the axis of symmetry of the trap. We outline an experimental method to study these excitations.

8 pages, 8 figures

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Cited by in corpus (9)

• Experimental demonstration of painting arbitrary and dynamic potentials for Bose-Einstein condensates
• Bose-Einstein condensation in a circular waveguide
• A ring trap for ultracold atoms
• Vortex signatures in annular Bose-Einstein condensates
• A Smooth, Inductively Coupled Ring Trap for Atoms
• Scale invariant thermodynamics of a toroidally trapped Bose gas
• Atom cooling with an atom-optical diode on a ring
• Geometric scale invariance as a route to macroscopic degeneracy: loading a toroidal trap with a Bose or Fermi gas
• Superfluid excitations in rotating two-dimensional ring traps