Charge frustration effects in capacitively coupled two-dimensional josephson-junction arrays

We investigate the quantum phase transitions in two capacitively coupled two-dimensional Josephson-junction arrays with charge frustration. The system is mapped onto the (Formula presented) and (Formula presented) anisotropic Heisenberg antiferromagnets near the particle-hole symmetry line and near the maximal-frustration line, respectively, which are in turn argued to be effectively described by a single quantum phase model. Based on the resulting model, it is suggested that near the maximal-frustration line the system may undergo a quantum phase transition from the charge-density wave to the supersolid phase, which displays both diagonal and off-diagonal long-range order.