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$SO(2)$-induced breathing patterns in multi-component Bose-Einstein condensates

In this work, we employ the $SO(2)$-rotations of a two-component, one-, two- and three-dimensional nonlinear Schrödinger system at and near the Manakov limit, to construct vector solitons and vortex structures. This way, stable stationary dark-bright solitons and their higher-dimensional siblings are transformed into robust oscillatory dark-dark solitons (and generalizations thereof), with and without a harmonic confinement. By analogy to the one-dimensional case, vector higher-dimensional structures take the form of vortex-vortex states in two dimensions and, e.g., vortex ring-vortex ring ones in three dimensions. We consider the effects of unequal (self- and cross-) interaction strengths, where the $SO(2)$ symmetry is only approximately satisfied, showing the dark-dark soliton oscillation is generally robust. Similar features are found in higher dimensions too, although our case examples suggest that phenomena such as phase separation may contribute to the associated dynamics. These results, in connection with the experimental realization of one-dimensional variants of such states in optics and Bose-Einstein condensates (BECs), suggest the potential observation of the higher-dimensional bound states proposed herein.