Non-Markovian quantum dynamics: Extended correlated projection superoperators

The correlated projection superoperator techniques provide a better understanding about how correlations lead to strong non-Markovian effects in open quantum systems. Their superoperators are independent of initial state, which may not be suitable for some cases. To improve this, we develop a new approach, that is extending the composite system before use the correlated projection superoperator techniques. Such approach allows choosing different superoperators for different initial states. We apply these techniques to a simple model to illustrate the general approach. The numerical simulations of the full Schr\"{o}dinger equation of the model reveal the power and efficiency of the method.