Quantum interference in time-delayed nonsequential double ionization

We perform a systematic analysis of quantum interference in nonsequential double ionization focusing on the recollision excitation with subsequent ionization (RESI) mechanism, employing the strong-field approximation (SFA). We find that interference has a major influence on the shape, localization, and symmetry of the correlated electron momentum distributions. In particular, the fourfold symmetry with regard to the parallel momentum components observed in previous SFA studies is broken. Two types of interference are observed and thoroughly analyzed, namely that caused by electron indistinguishability and intracycle events, and that stemming from different excitation channels. We find that interference is most prominent around the diagonal and antidiagonal in the parallel-momentum plane and provide fully analytical expressions for most interference patterns encountered. We also show that this interference can be controlled by an appropriate choice of phase and excited-state geometry. This leads a to myriad of shapes for the RESI distributions including correlated, anticorrelated, and ring shaped.