M.Sc Thesis

M.Sc StudentKushnir Maria
SubjectTransport and Weak Localization of Spin S Particles:
Application to the Atom-Photon System
DepartmentDepartment of Physics
Supervisor PROF. Eric Akkermans


This thesis deals with an investigation of the weak localization of spin S particles. The weak localization corrections have been calculated and experimentally observed in the case of electrons. Weak localization corrections to the conductivity Δσ have been predicted and measured for spin 1/2 problem, giving rise to anti-localization regime. It is the main aim of this thesis to extend the present status by describing weak localization of spin 1 particles. We analyze the problem by presenting a new technique able to evaluate weak localization of spin S particles - we introduce Hikami box in the presence of particles with arbitrary spin. Applying that technique to the spin 1/2 problem we calculate the weak localization correction to the diffusion coefficient ΔD, and we recover the Einstein relation Δσ = se2ρΔD to first order in the disorder and beyond the scalar case. In addition, using the Landauer approach, we calculate the conductance and the weak localization correction to it in the presence of spin-orbit interaction.

Another case of interest is the multiple scattering of light by atoms with internal structure. For that problem, using the former technique, we find the averaged transmission coefficient and the weak localization correction to it as a function of polarization. In addition we obtain weak localization correction to the diffusion coefficient both for classical and degenerate atoms. Those results lead to three interesting conclusions: a) For the classical scatterers there is a possibility for weak localization. b) The internal degrees of freedom destroy this effect, so that there is no localization. c) There is no anti-localization for the light.