Investigation of the limits of the secular and Markov approximations in the dissipative dynamics of laser-aligned molecules

¹ Laboratoire Interdisciplinaire CARNOT de Bourgogne, UMR 6303 CNRS-Université de Bourgogne, BP 47870, 21078 Dijon, France
² State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200241, China and Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China
³ Institut des Sciences Moléculaires d’Orsay, CNRS, Université Paris-Saclay, F-91405 Orsay, France
⁴ Laboratoire de Météorologie Dynamique/IPSL, CNRS, École polytechnique, Institut Polytechnique de Paris, Sorbonne Université, École Normale Supérieure, Université PSL, F-91120 Palaiseau, France

^* e-mail: manon.bournazel@u-bourgogne.fr

Published online: 18 October 2023

Abstract

We point out the breakdown of two approximations widely used to describe decoherence in open quantum systems, the secular and Markov approximations. We probe their limits by studying the influence of pressure on the alignment revivals (echoes) created in properly chosen gas mixtures (HCl and CO2, pure and diluted in He) by one (two) intense and short laser pulse(s). Experiments, as well as predictions using molecular dynamics simulations, consistently demonstrate in some of the aforementioned systems the break-down of these approximations at very short times (<15 ps) after the laser kick(s).