Histogram of density matrix of two qubits at scaled time τ = 1 with initial state |ΨAA(0)〉=|e〉⊗12(|e〉+|g〉) for strong coupling regime, i.e., R = 10 with (a) β = 0 and (b) β = 15 × 10⁻⁹. In these plots ω₀/λ = 1.5 × 10⁹.