The shortest simulation-box for time-dependent computation of wave packets in open system

A novel algorithm for a reduction of the computational burden associated to the time-dependent simulation of quantum transport with pure states is presented. The algorithm is based on using the superposition principle and the analytical knowledge of the free time-evolution of an initial state outside of the active region, together with absorbing layers. It is specially suited to study (many-particle and high-frequency effects) quantum transport, but it can also be applied to any other research field where the initial time-dependent pure state is located outside of the active region. Numerical results for a 1D system with the shortest simulation box imply a reduction of the computational burden of more than one order of magnitude with a negligible error.