Complete transfer of populations from a single state to a pre-selected superposition of states using Piecewise Adiabatic Passage

We develop a method for executing robust and selective transfer of populations between a single level and pre-selected superpositions of energy eigenstates. Viewed in the frequency domain, our method amounts to executing a series of simultaneous adiabatic passages into each component of the target superposition state. Viewed in {the} time domain, the method works by accumulating the wavefunction of the target wave packet as it revisits the Franck Condon region, in what amounts to an extension of the Piecewise Adiabatic Passage technique [ Shapiro et.al., Phys. Rev. Lett. 99, 033002 (2007)] to the multi-state regime. The viability of the method is verified by performing numerical tests for the Na_2 molecule.