Coherent and Incoherent Multiple Scattering

TL;DR

This paper compares coherent and incoherent models of light scattering in disordered systems, showing that an incoherent model can replicate many features of the scattering process, but the force on atoms is not a good coherence indicator.

Contribution

It demonstrates that incoherent models can effectively reproduce multiple scattering features typically associated with coherence effects in disordered media.

Findings

Incoherent model reproduces scattering features well

Force on atoms does not reveal coherence effects

Comparison highlights limitations of using atomic recoil as a coherence probe

Abstract

We compare two different models of transport of light in a disordered system with a spherical Gaussian distribution of scatterers. A coupled dipole model, keeping into account all interference effects, is compared to an incoherent model, using a random walk of particles. Besides the well known coherent backscattering effect and a well pronounced forward lobe, the incoherent model reproduces extremely well all scattering features. In an experiment with cold atoms, we use the momentum recoil imparted on the center of mass of the sample as a partial probe of the light scattering properties. We find that the force acting on the center of mass of the atoms is not well suited to exhibit the coherence effects in light propagation under multiple scattering conditions.