Numerical operator method for the real time dynamics of strongly-correlated quantum impurity systems far from equilibrium

TL;DR

This paper introduces a numerical operator method to study the real-time dynamics of strongly-correlated quantum impurity systems out of equilibrium, applicable across various interaction strengths and bias voltages, overcoming previous finite-size limitations.

Contribution

The authors develop a versatile numerical approach for non-equilibrium quantum impurity models that works at zero temperature and for strong interactions, surpassing existing methods in scope and accuracy.

Findings

Good agreement with quantum Monte Carlo at high bias

Accurate results at short times and low bias

Consistent with perturbation theory at weak interactions

Abstract

We develop a method for studying the real time dynamics of Heisenberg operators in strongly-interacting nonequilibrium quantum impurity models. Our method is applicable to a wide range of interaction strengths and to bias voltages beyond the linear response regime, works at zero temperature, and overcomes the finite-size limitations faced by other numerical methods. We compare our method with quantum Monte Carlo simulations at a strong interaction strength, at which no analytical method is applicable up to now. We find a very good coincidence of the results at high bias voltage, and in the short time period at low bias voltage. We discuss the possible reason of the deviation in the long time period at low bias voltage. We also find a good coincidence of our results with the perturbation results at weak interactions.