  We examine the effects of quantum fluctuations on a classical spin liquid
state in the fully-frustrated honeycomb lattice Bose Hubbard model using
quantum Monte Carlo simulations. Frustration is induced explicitly in the model
by modulating the sign of the interaction spatially around each lattice
hexagon. A superfluid to Mott insulating quantum phase transition can be
induced by varying the relative strength of the classical interaction and
quantum hopping. In the cases where the interaction has a regular spatial
modulation, hopping promotes a phase transition to a symmetry-broken
valence-bond solid state. When the interaction is forced to have no regular
pattern, the Mott insulating phase is found to be featureless and gapped,
making it an interesting candidate state for a quantum spin liquid arising in a
Hamiltonian with only nearest-neighbor interactions.
