  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
intra-cycle events, and that stemming from different excitation channels. We
find that interference is most prominent around the diagonal and anti-diagonal
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, anti-correlated and ring-shaped.
