D. M. Jezek

Dipolar condensates confined in a toroidal trap: ground state and vortices

We study a Bose-Einstein condensate of

Quantum cavitation in liquid helium

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Vortices in Bose-Einstein condensates with dominant dipolar interactions

atoms confined in a toroidal trap with a variable strength of

A density functional for liquid3He

s

K-Rb Fermi-Bose mixtures: Vortex states and sag

-wave contact interactions. We analyze the effects of the anisotropic nature of the dipolar interaction by considering the magnetization axis to be perpendicular to the trap symmetry axis. In the absence of a central repulsive barrier, when the trap is purely harmonic, the effect of reducing the scattering length is a tuning of the geometry of the system from a pancake-shaped condensate when it is large to a cigar-shaped condensate for small scattering lengths. For a condensate in a toroidal trap, the interaction in combination with the central repulsive Gaussian barrier produces an azimuthal dependence of the particle density for a fixed radial distance. We find that along the magnetization direction the density decreases as the scattering length is reduced but presents two symmetric density peaks in the perpendicular axis. For even lower values of the scattering length we observe that the system undergoes a dipolar-induced symmetry breaking phenomenon. The whole density becomes concentrated in one of the peaks, resembling an origin-displaced cigar-shaped condensate. In this context we also analyze stationary vortex states and their associated velocity fields, finding that these also show a strong azimuthal dependence for small scattering lengths. The expectation value of the angular momentum along the

Interaction-driven effects on two-component Bose-Einstein condensates

z

Quantum cavitation in liquid 3 He : Dissipation effects

direction provides a qualitative measure of the difference between the velocity in the different density peaks.

Generating vortex rings in Bose-Einstein condensates in the line-source approximation

Using a functional-integral approach, we have determined the temperature below which cavitation in liquid helium is driven by thermally assisted quantum tunneling. For both helium isotopes, we have obtained the crossover temperature in the whole range of allowed negative pressures. Our results are compatible with recent experimental results on {sup 4}He. {copyright} {ital 1996 The American Physical Society.}

Two-mode effective interaction in a double-well condensate

We present full three-dimensional numerical calculations of single vortex states in rotating dipolar condensates. We consider a Bose-Einstein condensate of

Stability of vortex lines in liquid {sup 3}He-{sup 4}He mixtures at zero temperature

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