Strong-field rotational kicks and ballistic alignment of Hubbard molecules

When a molecular ensemble interacts with a linearly polarized femtosecond laser pulse, the molecules receive differentiated rotational kicks, which lead to a field-free alignment in the ensemble in the pulse wake and periodic revivals of this alignment manifested as induced birefringence. We study how the interplay of many-body effects in the molecular electronic system and the effects of transient nonadiabatic charge localization determines the character of the rotational kicks in the strong-field interaction regime. We consider the electron-electron interaction in a model diatomic molecule in the framework of the Hubbard Hamiltonian, follow the electronic subsystem evolution during the laser pulse, and find the resulting rotational wavefunction as this evolution reflects on the nuclear degrees of freedom. The ensuing rotational wavepacket determines the ballistic dynamics of alignment and its revivals, quantified by the time-dependent alignment parameter. We trace drastic changes in the patterns of these dynamics in response to the laser intensity increase, conditioned by the tunnel matrix element and the repulsion parameter in the model molecules. .