From thermal equilibrium to nonequilibrium quench dynamics: A conserving approximation for the interacting resonant-level

Yuval Vinkler

We present a conserving approximation for the interacting resonant level model for the equilibrium as well as for the non-equilibrium situation. We will set the stage by a careful analytical analysis of the properties of our conserving approximation and comparison to well known results in equilibrium, and then we proceed to the calculation of the steady-state current through a two-lead device and extent our non-equilibrium calculation to quenches. We show analytically and numerically the origin of the surprising negative differential conduction at large bias voltages and investigate the time evolution of the current, using a two-time Keldysh Green function approach.