Martin Nuss, Martin Ganahl, Hans Gerd Evertz, Enrico Arrigoni, Wolfgang von der Linden
We study the time evolution and steady-state of the charge current in a Single Impurity Anderson Model, using Matrix Product States techniques. A non equilibrium situation is imposed by applying a bias voltage across one-dimensional tight binding leads. Focusing on particle-hole symmetry, we extract current-voltage characteristics from universal low bias up to high bias regimes, where band effects start to play a dominant role. We discuss three quenches, which after strongly quench dependent transients yield the same steady-state current. Among these quenches we identify those favorable for extracting steady-state observables. The period of short time oscillations is shown to compare well to real-time renormalization group results for a simpler model of spinless fermions. We find indications that many body effects play an important role at high-bias-voltage and finite bandwidth of the metallic leads. The growth of entanglement entropy after a certain time-scale $\propto \Delta^{-1}$ is the major limiting factor for calculating the time evolution. We show that the magnitude of the steady-state current positively correlates with entanglement entropy. The role of high energy states for the steady-state current is explored by considering a damping term in the time evolution.
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http://arxiv.org/abs/1301.3068
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