The expectation values ⟨ ⟨ Γ Γ i Γ Γ j ⟩ ⟩ = tr ⁡ ⁡ { Γ Γ i Γ Γ j R 0 } are with respect to the bath degrees of freedom. By assuming rapid decay of these correlations (ideally ⟨ ⟨ Γ Γ i ( t ) Γ Γ j ( t ′ ) ⟩ ⟩ ∝ ∝ δ δ ( t − − t ′ ) ), above form of the Lindblad superoperator L is achieved.