Multilevel effect on ultrafast isotope-selective vibrational excitations: Quantum optimal control study

We demonstrate, using optimal control theory, that perfect isotope-selective molecular vibrational excitations on the ground-state potential curve in multilevel systems can be completed in much shorter time scales than those in two-level systems. We consider a gaseous isotopic mixture of cesium iodide (133CsI and 135CsI) and, using two-level and multilevel systems, try to obtain electric fields that drive different isotopes into different vibrational levels. As a result, we find that in multilevel systems isotope-selective excitation processes can be controlled much faster, which we call multilevel effect. It is likely that this effect makes use of the large isotope shifts of higher vibrational levels than the lowest two.