Multilevel quantum interference in the formation of high-order fractional molecular alignment echoes

We theoretically investigate the formation of the high-order fractional alignment echo in OCS molecule and systematically study the dependence of echo intensity on the intensities and time delay of the two excitation pulses. Our simulations reveal an intricate dependence of the intensity of high-order fractional alignment echo on the laser conditions. Based on the analysis with rotational density matrix, this intricate dependence is further demonstrated to arise from the interference of multiple quantum pathways that involve multilevel rotational transitions. Our result provides a comprehensive multilevel picture of the quantum dynamics of high-order fractional alignment echo in molecular ensembles, which will facilitate the development of rotational echo spectroscopy. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Automated summary

In this study, we theoretically investigate the formation of high-order fractional alignment echo in OCS molecules and analyze the intricate dependence of echo intensity on laser conditions. Through analysis with rotational density matrix, we demonstrate that the complex dependence arises from interference of multiple quantum pathways involving multilevel rotational transitions. The results provide a comprehensive multilevel picture of quantum dynamics in molecular ensembles for the development of rotational echo spectroscopy.