Wavelet analysis of quantum transient transport in a quantum dot.

We investigate effects of switching speed of a bias voltage on a time-dependent current in a quantum dot with a single energy level, weakly coupled with two electrodes. Our simulations based on non-equilibrium Green's function formalism show that the transient current in the case of the high speed oscillates around the value of the stationary current. On the other hand, the current in the opposite case monotonically changes with time. This difference is explained in terms of the wavelet spectra of the currents, which mainly consist of two time-frequency domains with high intensities. [ABSTRACT FROM AUTHOR]