Topological Structure of Vortices in Multicomponent Bose-Einstein Condensates

The structure of the vortex in a two-component Bose-Einstein condensate is studied by the method of Dirac δ function. The vortex can be characterized by the Brouwer degree and Hopf index, i.e., β₁η₁, β₂η₂. The circulation of the vortex can be a fraction, which is different from the usual result for a one-component condensate. The kinetic helicity of vortices is calculated.