Inhomogeneous vortex matter
  We present a generalization of the continuum theory of vortex matter for non-uniform superfluid density. This theory explains the striking regularity of vortex lattices observed in Bose-Einstein condensates, and predicts the frequencies of long-wavelength lattice excitations. 
J. R. Anglin (1) and M. Crescimanno (2) ((1) Center for Ultracold   Atoms, Mass. Inst. Tech., (2) Center for Photon Induced ...