Numerical operator method for the real time dynamics of   strongly-correlated quantum impurity systems far from equilibrium
  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. 
Pei Wang, Guy Cohen, and Shaojun Xu
cond-mat.str-el cond-mat.mes-hall