Macroscopic angular momentum states of Bose-Einstein condensates in toroidal traps

摘要

We consider a Bose-Einstein condensate (BEC) of N atoms of repulsive interaction (approx) U(sub 0), in an elliptical trap, axially pierced by a Gaussian-intensity laser beam, forming an effective (quasi-2D) toroidal trap with minimum at radial distance (rho) = (rho)(sub p). The macroscopic angular momentum states (Psi)(sub l)((rho),(theta)) (approx) (radical)N(Phi)(sub l) ((rho))e(sup il(theta)) for integer l spread up to (rho) < or approx. (rho) (sub max) (approx) (NU(sub 0))(sup 1/4) >> (rho)(sub p). The spreading lowers rotational energies, so estimated low metastability barriers can support large l < or approx. l(sub max) (approx) (NU(sub 0))(sup 1/4), < or approx. 10 for typical parameters. The l-dependent density profile module (Phi)(sub l) ((rho))(sup 2) -(Phi)(sub 0)((rho))(sup 2) is a signature of BEC rotation. Results are insensitive to off-axis laser displacements (rho)(sub 0), for (rho) (sub 0) (rho)(sub max) << 1. (author). 23 refs, 2 figs.