We present a many-body theory for the interactions of two-dimensional exciton-polaritons beyond Born approximation. Taking into account Gaussian quantum fluctuations via Bogoliubov theory, we find that exciton-exciton scattering is strongly renormalized by light-matter coupling and acquires an inverse logarithmic dependence on lower polariton energy. As result, interaction strength may be enhan...

A Rytov series approximation for rough surface scattering is presented for an analytical description of the close relation of topographic statistics and topographic scattering. The Rytov series approximation is not subject to the stringent restrictions that apply to the Born series approximation. Numerical calculations of the Rytov series approximation are conducted for several benchmark models...

Diffuse optical tomography is used to find the optical parameters of a turbidmediumwith infrared red light. The problem is mathematically formulated as a nonlinear problem to find the solution for the diffusion operator mapping the optical coefficients to the photon density distribution on the boundary of the region of interest, which is also represented by the Born expansion with respect to th...

We present a detailed analysis of the role of the magnetic dipole-dipole interaction in cold and ultracold collisions. We focus on collisions between magnetically trapped NH molecules, but the theory is general for any two paramagnetic species for which the electronic spin and its space-fixed projection are (approximately) good quantum numbers. It is shown that dipolar spin relaxation is direct...