Spin depolarization for excitons in quantum wires

We consider theoretically the exchange coupling for independent excitons in quantum wires. The one-dimensional dispersions are complicated because the confinement energy due to the wire and the kinetic energy along the wire a xis are comparable in such structures. For weakly confining structures, we discuss different contributions for the spin depolarization in the presence of spin-conserving scatterings, which depend on the exchange couplings bet ween the various confined center-of-mass exciton motions. We also find that the spin coupling for free excitons increases with decreasing wire cross s ections in the strong confinement regime. Finally, we show for a gas of ind ependent excitons that the localization effects increase the spin-depolariz ation time and alters its temperature dependence.