Origin of correlated electron emission in double ionization of atoms

We investigate the origin of coordinated two-electron ionization of atoms under irradiation by short, intense laser pulses. We introduce a wave-function masking technique that separates the wave function into multiple components, based on the location of the population at some preselected time. Propagating these components separately allows a semiclassical tracking of populations and recollision events, with the full wave function being obtainable at any time as the coherent sum of the masked components. This method reveals that for our model system the most significant pathway to coordinated double ionization involves a correlated recollision event in which the returning electron comes back to the core in opposition to the laser force.