  Chiral topological superconductors are expected to appear as intermediate
states when a quantum anomalous Hall system is proximity coupled to an s-wave
superconductor and the magnetization direction is reversed. In this paper we
address the edge state properties of ordinary quantum Hall systems proximity
coupled to s-wave superconductors, accounting explicitly for Landau
quantization. We find that the appearance of topological superconducting phases
with an odd number of Majorana edge modes is dependent on the structure of the
system's vortex lattice. More precisely, vortex lattices containing odd number
of superconducting flux quanta per unit cell, always support an even number of
chiral edge channels and are therefore adiabatically connected to normal
quantum Hall insulators. We discuss strategies to engineer chiral topological
superconductivity in proximity-coupled quantum Hall systems by manipulating
vortex lattice structure.
