Time evolutions of error probabilities P_s for four initial states of atom in resonance. The four initial states are ground state (g, black square), excited state (e, red dot), superposition state (s, blue triangle) and maximally mixed state (m, green star). The Rabi frequencies are different in the different panels: (a) Ω₀ = 2.0κ, Ω₁ = 5.0κ, (b) Ω₀ = 1.0κ, Ω₁ = 4.0κ, (c) Ω₀ = 3.5κ, Ω₁ = 4.0κ, and (d) Ω₀ = 3.7κ, Ω₁ = 4.0κ.