Magnetic Field Driven Quantum Phase Transitions in Josephson Arrays

Understand

We have studied the magnetic-field-driven quantum phase transitions in Josephson junction arrays with a large coordination number.

• The characteristic energies were extracted in both the superconducting and insulating phases by integrating the current-voltage characteristics over a voltage range 2eV\leqk_B T.
• For the arrays with a relatively strong Josephson coupling, we observed duality between the energies in the superconducting and insulating phases.
• The arrays with a weaker Josephson coupling demonstrate an intermediate, "bad metal" regime in weak magnetic fields; this observation underlines the importance of vortex pinning at large scales and, presumably, emergent inhomogeneity in the presence of strong offset charge disorder.