Dissipation-Driven Superconductor-Insulator Transition in a Two-Dimensional Josephson-Junction Array

We have fabricated a two-dimensional array of Josephson junctions within 100 nm of a two-dimensional electron gas (2DEG) in a GaAs/AlGaAs heterostructure. The screening provided by the 2DEG causes the array to show superconducting behavior despite a large junction resistance. Varying the resistance per square of the 2DEG changes the dissipation in the electrodynamic environment of the array independently of any other parameters in the system. As the resistance increases, the current-voltage characteristics of the array change from superconducting to insulating in character.