  The nonequilibrium spectral properties of the Anderson impurity model with a
chemical potential bias are investigated within a numerically exact real time
quantum Monte Carlo formalism. The two-time correlation function is computed in
a form suitable for nonequilibrium dynamical mean field calculations.
Additionally, the evolution of the model's spectral properties are simulated in
an alternative representation, defined by a hypothetical but experimentally
realizable weakly coupled auxiliary lead. The voltage splitting of the Kondo
peak is confirmed and the dynamics of its formation after a coupling or gate
quench are studied. This representation is shown to contain additional
information about the dot's population dynamics. Further, we show that the
voltage-dependent differential conductance gives a reasonable qualitative
estimate of the equilibrium spectral function, but significant qualitative
differences are found including incorrect trends and spurious temperature
dependent effects.
