  We perform a detailed analysis of above threshold ionization (ATI) in atoms
within the strong field approximation (SFA) by considering spatially
inhomogeneous monochromatic laser fields. The locally enhanced field induced by
resonance plasmons is an example for such inhomogeneous fields. We investigate
how the individual pairs of quantum orbits contribute to the photoelectron
spectra and the angular electron momentum distributions. We demonstrate that
the quantum orbits have a very different behavior in the spatially
inhomogeneous field when compared to the homogeneous field. In the case of
inhomogeneous fields, the ionization and rescattering times differ between
neighboring cycles, despite the field being monochromatic. Indeed, the
contributions from one cycle may lead to a lower cutoff, while another may
develop a higher cutoff. Within our model, we show that the ATI cutoff extends
far beyond the semiclassical cutoff, as a function of inhomogeneity strength.
Furthermore, the angular momentum distributions have very different features
compared to the homogeneous case. For the neighboring cycles, the electron
momentum distributions do not share the same absolute momentum, and they do not
have the same yield
