Enhanced population transfer from the lowest to the highest level in the three-state ladder 5s→5p→5d of the rubidium atom by frequency-swept ultrashort laser pulses is observed if the frequency sweep first makes the pulse resonant with the 5s→5p transition, and later with the 5p→5d transition. With this ‘‘intuitive’’ scheme it is possible to achive complete population inversion via the intermediate level by two successive adiabatic passages. Complete inversion is also obtained by a ‘‘counterintuitive’’ direction of the frequency sweep, in which case population of the intermediate level during the pulse is strongly reduced.

• Received 13 July 1992

DOI:https://doi.org/10.1103/PhysRevLett.69.2062