(color online) F_ϕ as a function of the dimensionless quantity γ₀t for the initial state |ψ₁〉. Here, , and (a) λ = 5γ₀, Ω = 0.05γ₀; (b) λ = 5γ₀, Ω = 3γ₀; (c) λ = 0.05γ₀, Ω = 0.05γ₀; and (d) λ = 0.05γ₀, Ω = 3γ₀. The inset in (b) shows the case of Ω = 20γ₀.