with {θ n } ∈ [0, π] and {ϕ n } ∈ [0, 2π]. The expansion coefficients can be expressed from the usual recursive expression given in Eq. B1. Note that this is one convenient choice to write down spin coherence states, such that it is a generalization of Eq. 16 beyond the two level system. These angles can be viewed as the general Euler angles in multi-dimensional Bloch spheres 43 (also see Fig. for a schematic illustration). The notation of the expansion coefficients n|Ω used in Ref. 50 has a reversed order of diabatic state label and a π difference in the definition of θ n /2. The spin coherent states |Ω are normalized such that