The excitation operator approach to non-Markovian dynamics of quantum impurity models in the Kondo regime

We present the numerical excitation operator method for studying the real time dynamics of a small interacting quantum system coupled to a non-interacting fermionic reservoir by iteratively solving the Heisenberg equation of motion with the help of excitation operators. We apply this method to the decoherence dynamics of the single impurity Anderson model in the Kondo regime with a non-Markovian reservoir. We take full account of the environmental back-action and the electron-electron interaction, and find that the coexistence of the strong electron-electron interaction and a non-Markovian reservoir induces the coherence ringings, which will be suppressed by either driving the system away from the particle-hole symmetric point or changing the reservoir into a Markovian one. Copyright EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg 2013