We study QED in external electromagnetic fields using methods developed for
simulating lattice QCD. Our first project is to simulate QED in a constant
(in space and time) external magnetic field on a euclidean space-time lattice
using the Rational Hybrid Monte Carlo (RHMC) method. Observables we measure
include the condensate $\langle\bar{\psi}\psi\rangle$ and the effective
electron action after integrating out the fermion fields. We look for evidence
that the combined effect of the magnetic field and the electron-positron
attraction from QED produces a non-zero condensate in the limit of zero
electron mass, a non-perturbative effect analogous to spontaneous chiral
symmetry breaking. Very preliminary evidence is that such a condensate exists,
at least for strong external magnetic fields and unphysically large electric
charge. In addition, we are storing field configurations to measure the
expected distortions and screenings of the coulomb field of a charged particle
due to the vacuum polarization asymmetries produced by the magnetic field.
We hope also to measure the dynamical contribution to the electron mass
produced by the same mechanism that produces a finite condensate in the
zero input mass limit.