  The doped two-dimensional quantum dimer model is investigated by numerical
techniques on the square and triangular lattices, with significantly different
results. On the square lattice, at small enough doping, there is always a phase
separation between an insulating valence-bond solid and a uniform superfluid
phase, whereas on the triangular lattice, doping leads directly to a uniform
superfluid in a large portion of the RVB phase. Under an applied Aharonov-Bohm
flux, the superfluid exhibits quantization in terms of half-flux quanta,
consistent with Q=2e elementary charge quanta in transport properties.
