Universality and non-universality for a time-dependent quantum dot in the Kondo regime

We employ time-dependent non-crossing approximation for single electron transistor and calculate the transient response of the conductance for a variety of temperatures in infinitesimal bias when the dot-lead tunneling constant is suddenly changed such that the Kondo effect is present in the final state. In non-universal timescale, we see rapid oscillations. The frequency of these oscillations depends on the dot level and their amplitude is modulated by initial and final tunneling constants. We explain this observation qualitatively by exact solution of the resonant level model. In universal timescale, we compute the conductance for two systems which have different Kondo temperatures and test universality. Our results indicate that universality is well preserved as a function of T/T$_{K}$ in spite of tiny deviations at low temperatures.