Evolutionary optimization of rotational population transfer

We present experimental and numerical studies on control of rotational population transfer of NO(J = 1/2) molecules to higher rotational states. We are able to transfer 57% of the population to the J = 5/2 state and 46% to J = 9/2, in good agreement with quantum mechanical simulations. The optimal pulse shapes are composed of pulse sequences with delays corresponding to the beat frequencies of states on the rotational ladder. The evolutionary algorithm is limited by experimental constraints such as volume averaging and the finite laser intensity used, the latter to circumvent ionization. Without these constraints, near-perfect control (>98%) is possible. In addition, we show that downward control, moving molecules from high to low rotational states, is also possible.