Continuous tuning of quantum critical behavior in hybrid Josephson junction arrays

Abstract

We report finite-temperature scaling of voltage-driven quantum phase transitions in hybrid Josephson junction arrays. A dual-gate geometry separately tunes interisland coupling and proximity-induced superconductivity, providing access to superconducting, insulating, and metallic transport regimes. The critical resistivity and scaling exponent evolve continuously with electrostatic tuning. Where the three regimes converge, the critical resistivity approaches $h/4e^2$, consistent with the self-dual limit, while the scaling exponent approaches the quantum-percolation estimate. Tuning toward stronger insulating behavior raises the critical resistivity and shifts the scaling exponent toward the classical-percolation value, while both parameters decrease toward the metallic regime. These results connect scaling regimes previously reported in different two-dimensional superconducting systems through continuous electrostatic control.