  We investigate transient dynamic response of an Anderson impurity quantum dot
to a family of ramp-up driving voltage applied to the single coupling lead.
Transient current is calculated based on a hierarchical equations of motion
formalism for open dissipative systems [J. Chem. Phys. 128, 234703 (2008)]. In
the nonlinear response and nonadiabatic charging regime, characteristic
resonance features of transient response current reveal distinctly and
faithfully the energetic configuration of the quantum dot. We also discuss and
comment on both the physical and numerical aspects of the theoretical formalism
used in this work.
