  We investigate the doping of a geometrically frustrated spin ladder with
static holes by a complementary approach using exact diagonalization and
quantum dimers. Results for thermodynamic properties, the singlet density of
states, the hole-binding energy and the spin correlations will be presented.
For the undoped systems the ground state is non-degenerate, with
translationally invariant nearest-neighbor spin correlations. In the doped
case, we find that static holes polarize their vicinity by a localization of
singlets in order to reduce the frustration. This polarization induces short
range repulsive forces between two holes and an oscillatory behavior of the
long range two-hole energy. For most quantities investigated, we find very good
agreement between the quantum dimer approach and the results from exact
diagonalization.
