Bardeen-Josephson effect

The Bardeen-Josephson effect describes how a supercurrent—the flow of paired electrons without resistance—can pass between two superconductors separated by a thin insulating barrier. When the phase difference of the quantum wave functions in the two superconductors varies, it causes a current to flow across the barrier even without an applied voltage. This phenomenon is fundamental in superconducting electronics, such as quantum circuits, and demonstrates the unique quantum coherence properties of superconductors, where current is driven by phase relationships rather than traditional voltage differences.