Theoretical quantum design of pump-laser pulses for generating helical photon-dressed states

Abstract

Controlling the unidirectional rotation of π-electrons is a key challenge in the development of organic electronic and optoelectronic devices. In our recent study [Mineo et al., J. Chem. Phys. 161, 194311 (2024)], we explored the generation of unidirectional π-electron rotations in both low- and high-symmetry molecules by utilizing helical photon-dressed states. These states were formed using circularly or elliptically polarized laser fields within a minimal three-state electronic model under the frozen-nuclei approximation. However, that approach did not address the preparation of appropriate initial conditions or the tailored light–matter interactions required to create photon-dressed states. To overcome this limitation, it is crucial to consider a process that prepares the photon-dressed states from the electronic ground state through optical pumping with pulsed lasers. In this work, we analytically design such pulsed lasers to induce helical photon-dressed states in both low- and high-symmetry aromatic rings, starting from the ground state. We further incorporate the nuclear vibrational effects within the adiabatic approximation and apply those designed laser fields to low-symmetry aromatic rings. Finally, we numerically demonstrate the generation of angular momenta associated with the photon-dressed states using the analytically designed laser fields. Vibrational effects are found to selectively influence the stability of specific photon-dressed states.