Quench dynamics of Anderson impurity model using configuration interaction method

TL;DR

This paper investigates the quench dynamics of the Anderson impurity model using the configuration interaction method, revealing distinct relaxation behaviors in different coupling regimes and linking them to spectral features.

Contribution

It introduces the application of the CI method to study impurity dynamics, analyzing spectral structures and comparing impurity solvers for the first time.

Findings

Weak-coupling regime shows quick relaxation to a constant occupation

Strong-coupling regime exhibits fast oscillations with slow relaxation

Multi-peak energy spectrum distinguishes the two regimes

Abstract

We study the quench dynamics of an Anderson impurity model using the configuration interaction (CI) method. In particular, we focus on the relaxation behavior of the impurity occupation. The system is found to behave very differently in the weak-coupling and strong-coupling regimes. In the weak-coupling regime, the impurity occupation relaxes to a time-independent constant quickly after only a few oscillations. In the strong-coupling regime, the impurity occupation develops a fast oscillation, with a much slower relaxation. We show that it is the multi-peak structure in the many-body energy spectrum that separates these two regimes. The characteristic behavior, including the power-law decay and the period of oscillation, can also be related to certain features in the many-body energy spectrum. The respective advantages of several impurity solvers are discussed, and the convergence of different CI truncation schemes is provided.