We have recently demonstrated that a dense ensemble of two-level atoms driven by an electromagnetic field can be modelled by an effective single quantum system that has a time-varying decoherence rate [1]. This model compares very well to large-scale, mean-field simulations of the Maxwell-Lindblad equations for a cluster of approximately 4000 atoms. Our effective single particle theory provides a way to model optical interactions in clusters in which computational time can be reduced, and also a model in which the underlying physical processes involved in the system's evolution are much easier to understand. We use this theory to provide an explanation for the results of scattering experiments [2], in which high-intensity, short-duration, electromagnetic pulses were scattered off dielectric liquids such as water and carbon tetrachloride, and produced depolarized emission patterns.

[1] C. S. DiLoreto and C. Rangan, Phys. Rev. A 97: 013812, 2018.
[2] S. C. Rand, W.M. Fisher, and S. L. Oliveira, J. Opt. Soc. Am B, 25:1106, 2008.