If the basis states are orthonormal then ⟨ i | j ⟩ = δ i j {\displaystyle \langle i|j\rangle =\delta _{ij}} where i , j ∈ 1 , 2 {\displaystyle i,j\in {1,2}} and δ i j {\displaystyle \delta _{ij}} is the Kronecker delta, so c i = ⟨ i | ψ ⟩ {\displaystyle c_{i}=\langle i|\psi \rangle } . These two complex numbers may be considered coordinates in a two-dimensional complex Hilbert space.[1] Thus the state vector corresponding to the state | ψ ⟩ {\displaystyle |\psi \rangle } is