This suggests the dressed state | ψ ψ c ( p ) ⟩ ⟩ that couples to | ψ ψ e ( p ) ⟩ ⟩ = | e 0 , p ⟩ ⟩ is a more convenient basis state of the two ground states. The orthogonal basis state | ψ ψ n c ( p ) ⟩ ⟩ defined below does not couple to | ψ ψ e ( p ) ⟩ ⟩ at all.