Rotating Bose-Einstein condensates confined in an anharmonic potential

We consider bosonic atoms that rotate in an anharmonic trapping potential. Using numerical diagonalization of the Hamiltonian, we get evidence for various phases of the gas for different values of the coupling between the atoms and of the rotational frequency of the trap. These include vortex excitation of single and multiple quantization, the phase of center-of-mass excitation, and the unstable phase