  We investigate the finite time behavior of pair production from the vacuum by
time-dependent Sauter pulsed electric fields in spinor quantum electrodynamics
(QED). Using the exact analytic solution of the mode function, we find the
one-particle distribution function in momentum space. The longitudinal momentum
spectrum of particles shows oscillatory behavior at a finite time in a small
window of longitudinal momentum where the electric field diminishes to around
one-hundredth of its maximum magnitude and its oscillation time is close to
Compton time. This oscillation is asymmetric, i.e., the amplitude of
oscillation is maximum for negative longitudinal momentum compared to positive
rate. The change in the longitudinal momentum spectrum can occur due to the
quantum interference effect, and this quantum interference effect comes from
the result of dynamical tunneling. The transverse momentum spectrum shows the
Gaussian structure with a peak at zero transverse momentum when $t = 0$. After
$t \approx \tau/2$, the smooth Gaussian design becomes distorted, and we see
inconstancy in spectrum structure, either a dip at the origin with an off-axis
maximum or a peak at zero transverse momentum with small mountains up to $t
\approx 2{\tau}$ observed. After that, the spectrum shows a maximum height at
zero transverse momentum with weakly pronounced peaks.
