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Abstract: We study a Bose-Einstein condensate of 52Cr atoms confined in a toroidal trapwith a variable strength of s-wave contact interactions. We analyze the effectsof the anisotropic nature of the dipolar interaction by considering themagnetization axis to be perpendicular to the trap symmetry axis. In theabsence of a central repulsive barrier, when the trap is purely harmonic, theeffect of reducing the scattering length is a tuning of the geometry of thesystem: from a pancake-shaped condensate when it is large, to a cigar-shapedcondensate for small scattering lengths. For a condensate in a toroidal trap,the interaction in combination with the central repulsive Gaussian barrierproduces an azimuthal dependence of the particle density for a fixed radialdistance. We find that along the magnetization direction the density decreasesas the scattering length is reduced but presents two symmetric density peaks inthe perpendicular axis. For even lower values of the scattering length weobserve that the system undergoes a dipolar-induced symmetry breakingphenomenon. The whole density becomes concentrated in one of the peaks,resembling an origin-displaced cigar-shaped condensate. In this context we alsoanalyze stationary vortex states and their associated velocity field, findingthat this latter also shows a strong azimuthal dependence for small scatteringlengths. The expectation value of the angular momentum along the z directionprovides a qualitative measure of the difference between the velocity in thedifferent density peaks.

Autor: M. Abad, M. Guilleumas, R. Mayol, M. Pi, D. M. Jezek

Fuente: https://arxiv.org/

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