  Initial-state symmetry has been underappreciated in strong-field
spectroscopies, where laser fields dominate the dynamics. We demonstrate
numerically that the transverse photoelectron phase structure, arising from
this symmetry, is robust in strong-field rescattering, and manifests in
strong-field photoelectron spectra. Interpretation of rescattering experiments
need to take these symmetry effects into account. In turn, transverse
photoelectron phase structures may enable attosecond super-resolution imaging
with structured electron beams.
