  We analyze the spins of a Schwinger particle pair in a spatially uniform but
time dependent electric field. The particle pair's spins are in the maximally
entangled Bell state only if the particles' momenta are parallel to the
electric field. However if transverse momentum is present, the spins are not in
the maximally entangled Bell state. The reason is that the pair is created by
the external field, which also carries angular momentum, and the particle pair
can take away some of this external angular momentum.
