Quantized circular motion of a trapped Bose-Einstein condensate in laser beams: coherent rotation and vortices


 
Phys. Rev. A. 57, 4761-4769 (1998)     cond-mat/9711084    

One can understand that no vortex is created in a harmonic potential by realizing that the energy interval En+1 - En between two energy eigenstates (both the ground state and vortex states are eigenstates of the Hamiltonian) is constant. Therefore, if the transition between the ground state and the first vortex state is resonant, soon higher vortex states will be populated, too. A pure vortex state can never be achieved! The corresponding superposition of vortex states is equivalent to the circular motion shown on the previous page.
 

In an anharmonic trapping potential the energy interval En+1 - En is not constant and depends on n. Hence, if the transition between the ground state and the first vortex state is in resonance this will not be the case for the transition to higher vortex states. We therefore examined whether a rotating force can create a vortex state in an r4 potential. Our results demonstrate that this is the case. You may see the creation process in the following movie which is based on a numerical simulation.
 


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