Center-of-mass rotation and vortices in an attractive Bose gas (8 pages)

G. M. Kavoulakis

Yanzhi Zhang, Weizhu Bao

Yujin Guo, Yong Luo, Wen Yang

Mohd. Imran, M. A. H. Ahsan

Anssi Collin, Emil Lundh, Kalle‐Antti Suominen

The rotational properties of an attractively interacting Bose gas are studied using analytical and numerical methods. We study perturbatively the ground-state phase space for weak interactions, and find that in an anharmonic trap the rotational ground states are vortex or center-of-mass rotational states; the crossover line separating these two phases is calculated. We further show that the Gross-Pitaevskii equation is a valid description of such a gas in the rotating frame and calculate numerically the phase-space structure using this equation. It is found that the transition between vortex and center-of-mass rotation is gradual; furthermore, the perturbative approach is valid only in an exceedingly small portion of phase space. We also present an intuitive picture of the physics involved in terms of correlated successive measurements for the center-of-mass state.

Emil Lundh, Anssi Collin, Kalle‐Antti Suominen

A rotated and harmonically trapped Bose gas with attractive interactions is expected to either remain stationary or escape from the trap. Here we report that, on the contrary, in an anharmonic trapping potential the Bose gas with attractive interactions responds to external rotation very differently, namely, through center-of-mass motion or by formation of vortices.