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 axis 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 between the various confined center-of-mass exciton motions. We also find that the spin coupling for free excitons increases with decreasing wire cross sections in the strong confinement regime. Finally, we show for a gas of independent excitons that the localization effects increase the spin-depolarization time and alters its temperature dependence.