Clusters of exceptional points for a laser control of selective vibrational transfer

When a molecule is exposed to a laser field, all field-free vibrational states become resonances, with complex quasienergies calculated using Floquet theory. There are many ways to produce the coalescences of pairs of such quasienergies, with appropriate wavelength-intensity choices which define exceptional points (EP) in the laser parameter plane. We dress for the molecular ion H2+ an exhaustive map of these exceptional points which appear in clusters. Such clusters can be used to define several vibrational transfer scenarios implying more than a single exceptional point, exchanging single or multiple vibrational quanta. The ultimate goal is molecular vibrational cooling by transferring an initial (thermal, for instance) population on a final (ground, for instance) single vibrational state.

Clusters of exceptional points in the laser wavelength/intensity parameter plane are at the origin of a selective vibrational transfer strategy in the photodissociation of diatomic molecules. This could ultimately be used for molecular vibrational cooling.Highlights► We use Floquet formalism to calculate laser induced resonances in diatomics. ► Exceptional points (EP) correspond to resonance coalescence. ► Shaping a laser pulse by encircling an EP allows for selective vibrational transfers. ► Ultimately such transfers are expected to lead to molecular cooling strategies.