Vortex graphs as N-omers and CP(N-1) Skyrmions in N-component Bose-Einstein condensates

Stable vortex N-omers are constructed in coherently coupled N-component Bose-Einstein condensates. We classify all possible N-omers in terms of the mathematical graph theory and numerically construct all graphs for N=2,3,4. We also find that N-omers are well described as CP(N-1) skyrmions when inter-component and intra-component couplings are U(N) symmetric, and we evaluate their size dependence on the Rabi coupling.