Lopsided vortex cells in rotating Bose-Einstein condensates

The amplitude vertical bar Psi vertical bar of the wavefunction of a repulsive Bose-Einstein condensate in a two-dimensional axisymmetric harmonic trap decreases as we go from the center of the condensate towards its edge. Consequently the wavefunction amplitude at the edge of a vortex cell in a vortex lattice in a rotating repulsive condensate should be greater for the inner cells. Continuity of the wavefunction amplitude between neighboring cells requires then that vertical bar Psi vertical bar varies along the edge of each vortex cell, so that it is greater at the points that are closer to the center of the condensate. In other words, the wavefunction amplitude is lopsided in each vortex cell. We show this explicitly via an analytic variational calculation where a simple lopsided wavefunction amplitude is used for each vortex cell. This wavefunction amplitude varies continuously as we go from one cell to the next. The results agree quite well with experimental observations.