Short-pulse or strong-field breakup processes: a route to study entangled wave packets

Strong and/or short laser pulses provide one avenue for rapid separation of composite quantum systems. Daughter particles can exhibit subtle aspects of quantum entanglement. We show that a Gaussian approximation provides a unifying overview of rapidly separating systems in many contexts, and propose using combined single-particle and coincidence measurements of wave-packet widths of bipartite systems for experimental observation of the degree of entanglement.