From this, the STIRAP counter-intuitive pulse sequence can be deduced. At θ θ = 0 which corresponds the presence of only the Stokes field ( Ω Ω S ≫ ≫ Ω Ω P ), the dark state exactly corresponds to the initial state | 1 ⟩ ⟩ . As the mixing angle is rotated from 0 to π π / 2 , the dark state smoothly interpolates from purely state | 1 ⟩ ⟩ to purely state | 3 ⟩ ⟩ . The latter θ θ = π π / 2 case corresponds to the opposing limit of a strong pump field ( Ω Ω P ≫ ≫ Ω Ω S ). Practically, this corresponds to applying Stokes and pump field pulses to the system with a slight delay between while still maintaining significant temporal overlap between pulses; the delay provides the correct limiting behavior and the overlap ensures adiabatic evolution. A population initially prepared in state | 1 ⟩ ⟩ will adiabatically follow the dark state and end up in state | 3 ⟩ ⟩ without populating state | 2 ⟩ ⟩ as desired. The pulse envelopes can take on fairly arbitrary shape so long as the time rate of change of the mixing angle is slow compared to the energy splitting with respect to the non-dark states. This adiabatic condition takes its simplest form at the single-photon resonance condition Δ Δ = 0 where it can be expressed as