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Breathing Modes in Rotating Bose-Condensed Gas: An Exact Diagonalization Study
We present an exact diagonalization study of the breathing mode collective
excitations for a rotating Bose-Einstein condensate of spinless bosons
interacting via repulsive finite-range Gaussian potential and harmonically
confined in quasi-two-dimension. The yrast state and the low-lying excited
states are variationally obtained in given subspaces of the quantized total
angular momentum employing the beyond lowest Landau level approximation in
slowly rotating regime with . For a given , the low-energy
eigenspectra (bands) are obtained in weakly to moderately interacting regime.
Further, for a given interaction, the split in low-lying eigenenergies with
increasing is the precursor to spontaneous symmetry breaking of the
axisymmetry associated with the entry of the first vortex. With increase in
repulsive interaction, the value of the first breathing mode increases for
stable total angular momentum states L=0~\mbox{and}~N, but decreases for
intermediate metastable states. The position of the observed first
breathing modes in the eigenspectrum remains unchanged as the interaction is
varied over several orders of magnitude.Comment: 5 pages, 3 figures, RevTex two colum
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