Population and coherence control by three-pulse four-wave mixing

Control of coherence and population transfer between the ground and excited states is reported using three-pulse four-wave mixing. The inherent vibrat ional dynamics of the system are utilized in timing the pulse sequence that controls the excitation process. A slight alteration in the pulse sequence timing causes a change in the observed signal from coherent vibration in t he ground state to coherent vibration in the excited state. This control is demonstrated experimentally for molecular iodine. The theoretical basis fo r these experiments is discussed in terms of the density matrix for a multi level system. (C) 1999 American Institute of Physics. [S0021-9606(99)03233- X].