Quantum Monte Carlo Study of a Disordered 2-D Josephson Junction Array

We have studied the superconducting-insulating phase transition in a disordered two-dimensional Josephson junction array, using quantum Monte Carlo techniques. We consider disorder in both the capacitive energies and in the values of the offset charges. The calculated phase diagram shows that the lobe structure of the phase diagram disappears for sufficiently strong disorder in the offset charge. Our results agree quite well with previous calculations carried out using a mean-field approximation.