Equation Icon  SvYacZ(Ω) = 𝒴𝒴𝒴 †(Ω)⟨ˆa (Ω ) ∘ ˆa †(Ω )⟩vac𝒵𝒵𝒵 (Ω) = 𝒴𝒴𝒴 †(Ω)𝕊vac(Ω)𝒵𝒵𝒵 (Ω) 𝒴𝒴𝒴†(Ω )𝒵𝒵𝒵 (Ω ) 𝒴 ∗(Ω)𝒵 (Ω ) + 𝒴∗(Ω )𝒵 (Ω ) = ------------= --c-----c-------s-----s----, (91 ) 2 2