SUPERCONDUCTOR-INSULATOR TRANSITION IN A TUNABLE DISSIPATIVE ENVIRONMENT

We study the influence of a tunable dissipative environment on the dyn amics of Josephson junction arrays near the superconductor-insulator t ransition. The experimental realization of the environment is a two di mensional electron gas coupled capacitively to the array. This setup a llows for the well controlled tuning of the dissipation by changing th e resistance of the two dimensional electron gas. The capacitive coupl ing cuts off the dissipation at low frequencies. We determine the phas e diagram and calculate the temperature and dissipation dependence of the array conductivity. We find good agreement with recent experimenta l results.