  We suggest and study designed defects in an otherwise periodic potential
modulation of a two-dimensional electron gas as an alternative approach to
electron spin based quantum information processing in the solid-state using
conventional gate-defined quantum dots. We calculate the band structure and
density of states for a periodic potential modulation, referred to as an
antidot lattice, and find that localized states appear, when designed defects
are introduced in the lattice. Such defect states may form the building blocks
for quantum computing in a large antidot lattice, allowing for coherent
electron transport between distant defect states in the lattice and tunnel
coupling of neighboring defect states with corresponding electrostatically
controllable exchange coupling between different electron spins.
