Microscopic mechanisms of dephasing due to electron-electron interactions

We develop a nonperturbative numerical method to study tunneling of a single electron through an Aharonov-Bohm ring where several strongly interacting electrons are bound. Inelastic processes and spin-flip scattering are taken into account. The method is applied to study microscopic mechanisms of dephasing in a nontrivial model. We show that the electron-electron interactions described by the Hubbard Hamiltonian lead to strong dephasing: the transmission probability at flux $\Phi =\pi$ is high even at small interaction strength. In addition to inelastic scattering, we identify two energy-conserving mechanisms of dephasing: symmetry-changing and spin-flip scattering. The many-electron state on the ring determines which of these mechanisms will be at play: transmitted current can occur either in elastic or inelastic channels, with or without changing the spin of the scattering electron.