Equation Icon  † † 2πSY (Ω )δ(Ω − Ω ′) = ⟨ψ|NˆY (Ω ) ∘ ˆN Y(Ω′)|ψ ⟩ = ⟨ ˆNY (Ω) ∘NˆY (Ω′)⟩. (87 )