Attosecond control of correlated electron dynamics in strong-field nonsequential double ionization by parallel two-color pulses

We theoretically investigate the correlated electron dynamics in strong-field nonsequential double ionization (NSDI) of Ar by the parallel two-color pulses consisting of 800- and 400-nm laser fields with the semiclassical ensemble model. Our calculations show that the momentum distributions of Ar2+ in the direction parallel to the polarization of laser field exhibit the single- or double-hump structure, depending on the relative phase of the two-color fields. Back analysis of the NSDI trajectories reveals that recollision of returning electron is well confined in a time window of several attoseconds, and the position of which can be controlled with attosecond precision by changing the relative phase of the two-color fields. Thus, the recollision energy is accurately controlled with the two-color fields. As a consequence, the time delay between the double ionization and recollision changes with the relative phase, resulting in the relative-phase-dependent ion momentum distributions. More interestingly, the different peaks of ion momentum spectra result from the NSDI events with different time delays between double ionization and recollision. Thus, the corresponding correlated electron dynamics for different peaks in the ion momentum distributions can be directly determined in the two-color fields.