The resonance condition of any Λ Λ -type Raman process requires that the difference in the two photon energies match the difference in energy between the states at the "legs" of the Λ Λ , here the ground states | g − − 1 ⟩ ⟩ , | g 1 ⟩ ⟩ , identified above. In experimental settings, this condition is realized when the detunings of the cycling and repumper frequencies in respect to the | g − − 1 ⟩ ⟩ → → | e 0 ⟩ ⟩ and | g 1 ⟩ ⟩ → → | e 0 ⟩ ⟩ transition frequencies, respectively, are equal.