Mesoscopic scattering of spin s particles

TL;DR

This paper develops a unified theoretical framework for mesoscopic spin physics by systematically diagonalizing scattering vertices, applicable to electrons, photons, and other quantum particles, to better understand weak localization effects.

Contribution

It provides a comprehensive diagonalization of diffuson and cooperon vertices for any spin and impurity interaction, unifying mesoscopic spin physics across different quantum particles.

Findings

Derived general eigenvalues and projectors for scattering vertices.

Applied the framework to spin-flip scattering of electrons with magnetic impurities.

Reviewed photon scattering in cold atomic gases.

Abstract

Quantum effects in weakly disordered systems are governed by the properties of the elementary interaction between propagating particles and impurities. Long range mesoscopic effects due to multiple scattering are derived by iterating the single scattering vertex, which has to be appropriately diagonalized. In the present contribution, we present a systematic and detailed diagonalisation of the diffuson and cooperon vertices responsible for weak localisation effects. We obtain general expressions for eigenvalues and projectors onto eigenmodes, for any spin and arbitrary elementary interaction with impurities. This description provides a common frame for a unified theory of mesoscopic spin physics for electrons, photons, and other quantum particles. We treat in detail the case of spin-flip scattering of electrons by freely orientable magnetic impurities and briefly review the case of photon scattering from degenerate dipole transitions in cold atomic gases.