Collective modes of trapped spinor Bose condensates (1608.01020v1)

Abstract: We study the richer structures of quasi-one-dimensional Bogoliubov-de Genes collective excitations of F = 1 spinor Bose-Einstein condensate in a harmonic trap potential loaded in an optical lattice. Employing a perturbative method we report general analytical expressions for the confined collective polar and ferromagnetic Goldstone modes. In both cases the excited eigenfrequencies are given as function of the 1D effective coupling constants, trap frequency and optical lattice parameters. It is shown that the main contribution of the optical lattice laser intensity is to shift the confined phonon frequencies. Moreover, for high intensities, the excitation spectrum becomes independent of the self-interaction parameters. We reveal some features of the evolution for the Goldstone modes as well as the condensate densities from the ferromagnetic to the polar phases.