On the control of the populations of atomic states through the use of a static electric field, pulsed lasers, and competing two-photon excitation mechanisms Original Research Article

The control of excited state atomic populations, through the use of a combination of a static electric field, two pulsed lasers, and competitions involving two different two-photon excitation mechanisms, and different excitation pathways, from the ground state is discussed. One of the mechanisms requires non-zero diagonal dipole moment matrix element differences between the `groundʹ and the `finalʹ excited states, which for atoms generally requires the application of a static electric field; the other mechanism requires a virtual state. Analytical and numerical results for a three-level atomic model, the minimal model for such a study, are used to help discuss the control of the final state atomic population via changes in the relative phase, or the angle between the polarization vectors, or the frequencies, of the two lasers. While many aspects of the atomic control scenarios are analogous to those discussed recently for dipolar molecules (in the absence of a static field), the populations of the final atomic states possess time-dependent oscillations (quantum beats) after the laser–atom interactions have ceased due to the presence of the static electric field.