Equation Icon  SvaYc(Ω ) = 𝒴𝒴𝒴 †(Ω)⟨ˆa (Ω) ∘ ˆa †(Ω )⟩vac𝒴𝒴𝒴 (Ω) = 𝒴𝒴𝒴 †(Ω)𝕊vac(Ω)𝒴𝒴𝒴 (Ω) 𝒴𝒴𝒴†(Ω )𝒴𝒴𝒴(Ω ) |𝒴 (Ω )|2 + |𝒴 (Ω)|2 = -----------= --c----------s-----, (88 ) 2 2