Fig. 1. The dependence of Cd on θ and ϕ, where the superposition coefficients of the initial state α=β=(1/2)^1/2 and the noise strength d=0.2

Fig. 2. Variation of Cdwith θ and d for the case of ϕ=π/2 (optimal value)

Fig. 3. Variation of Cdwith ϕ and d for the case of θ=π/2 (optimal value)

Fig. 4. The dependence of Cd on θ and ϕ

Fig. 5. Variation of Cd with θ and d

Fig. 6. The relationship of d_Lwith α and θ, where ϕ=ϕb