  I present an exact solution for the Heisenberg picture, Dirac electron in the
presence of an electric field which depends arbitrarily upon the light cone
time parameter $x^+ = (t+x)/\sqrt{2}$. This is the largest class of background
fields for which the mode functions have ever been obtained. The solution
applies to electrons of any mass and in any spacetime dimension. The
traditional ampiguity at $p^+ = 0$ is explicitly resolved. It turns out that
the initial value operators include not only $(I + \gamma^0 \gamma^1) \psi$ at
$x^+ = 0$ but also $(I - \gamma^0 \gamma^1) \psi$ at $x^- = -L$. Pair creation
is a discrete and instantaneous event on the light cone, so one can compute the
particle production rate in real time. In $D=1+1$ dimensions one can also see
the anomaly. Another novel feature of the solution is that the expectation
value of the currents operators depends non-analytically upon the background
field. This seems to suggest a new, strong phase of QED.
