Stark-induced adiabatic Raman passage examined through the preparation of D₂ (v = 2, j = 0) and D₂ (v = 2, j = 2, m =...

We study the conditions that must be met for successful preparation of a large ensemble in a specific target quantum state using Stark-induced adiabatic Raman passage (SARP). In particular, we show that the threshold condition depends on the relative magnitudes of the Raman polarizability (r_0v) and the difference of the optical polarizabilities (Δα_00→vj) of the initial (v = 0, j = 0) and the target (v, j) rovibrational levels. Here, v and j are the vibrational and rotational quantum numbers, respectively. To illustrate how the operation of SARP is controlled by these two parameters, we experimentally prepared D₂ (v = 2, j = 0) and D₂ (v = 2, j = 2, m = 0) in a beam of D₂ (v = 0, j = 0) molecules using a sequence of partially overlapping pump and Stokes laser pulses. By comparing theory and experiment, we were able to determine the Raman polarizability r₀₂ ≈ 0.3 × 10^-41 Cm/(V/m) and the difference polarizabilities Δα_00→20 ≈ 1.4 × 10^-41 Cm/(V/m) and Δα_00→22 ≈ 3.4 × 10^-41 Cm/(V/m) for the two Raman transitions. Our experimental data and theoretical calculations show that because the ratio r/Δα is larger for the (0,0) → (2,0) transition than the (0,0) → (2,2) transition, much less optical power is required to transfer a large population to the (v = 2, j = 0) level. Nonetheless, our experiment demonstrates that substantial population transfer to both the D₂ (v = 2, j = 0) and D₂ (v = 2, j = 2, m = 0) is achieved using appropriate laser fluences. Our derived threshold condition demonstrates that with increasing vibrational quantum number, it becomes more difficult to achieve large amounts of population transfer.