  The process of coherent creation of particle - hole excitations by an
electric field in graphene is quantitatively described using a dynamic "first
quantized" approach. We calculate the evolution of current density, number of
pairs and energy in ballistic regime using the tight binding model. The series
in electric field strength $E$ up to third order in both DC and AC are
calculated. We show how the physics far from the two Dirac points enters
various physical quantities in linear response and how it is related to the
chiral anomaly. The third harmonic generation and the imaginary part of
conductivity are obtained. It is shown that at certain time scale
$t_{nl}\propto E^{-1/2}$ the physical behaviour dramatically changes and the
perturbation theory breaks down. Beyond the linear response physics is explored
using an exact solution of the first quantized equations. While for small
electric fields the I-V curve is linear characterized by the universal minimal
resistivity $\sigma =\pi /2(e^{2}/h)$%, at $t>t_{nl}$ the conductivity grows
fast. The copious pair creation (with rate $E^{3/2}$), analogous to Schwinger's
electron - positron pair creation from vacuum in QED, leads to creation of the
electron - hole plasma at ballistic times of order $t_{nl}$. This process is
terminated by a relaxational recombination.
