EPJ Web of Conferences

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

M. Bournazel, Junyang Ma, Franck Billard, E. Hertz, Jian Wu, C. Boulet, Jean‐Michel Hartmann, O. Faucher

Published Jan 1, 2023• 0 citations

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).

DOI: 10.1051/epjconf/202328708012

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EPJ Web of Conferences

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

M. Bournazel, Junyang Ma, Franck Billard, E. Hertz, Jian Wu, C. Boulet, Jean‐Michel Hartmann, O. Faucher

Published Jan 1, 2023• 0 citations

Publisher

Abstract

DOI: 10.1051/epjconf/202328708012

Related papers

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We experimentally and theoretically investigate the ultrafast collisional dynamics of a symmetric-top molecule (

{\mathrm{C}}_{2}{\mathrm{H}}_{6}

) in pure gas and mixtures with He at high density by employing the rotational alignment echo created by a pair of time-delayed intense laser kicks. The decrease of the amplitude of the echo when increasing the delay between the two laser pulses, reflecting the collisional relaxation of the system, is measured by probing the transient birefringence induced in the medium. The theoretical predictions, carried using purely classical molecular dynamics simulations, reproduce well the observed features, as demonstrated previously for a linear molecule. The analysis shows that the dissipation of the ethane alignment, despite the fact that this species has an extra rotational degree of freedom as compared to a linear molecule, barely involves more complex collisional relaxation channels due to characteristics of the ${\mathrm{C}}_{2}{\mathrm{H}}_{6}\ensuremath{-}{\mathrm{C}}_{2}{\mathrm{H}}_{6}$ and ${\mathrm{C}}_{2}{\mathrm{H}}_{6}\ensuremath{-}\mathrm{He}$ interactions. However, our findings reveal that the dissipative dynamics of a symmetric-top molecule can be properly approached using the recently discovered rotational alignment echoes, which, so far, have been only tested for probing rotational decoherence of simpler (linear) molecules.