  Nonlinear modifications of quantum mechanics generically lead to nonlocal
effects which violate relativistic causality. We study these effects using the
functional Schrodinger equation for quantum fields and identify a type of
nonlocality which causes nearly instantaneous entanglement of spacelike
separated systems. We describe a simple example involving widely separated
wave-packet (coherent) states, showing that nonlinearity in the Schrodinger
evolution causes spacelike entanglement, even in free field theory.
