Josephson effect: Cooper pair tunneling

This lecture covers the Josephson effect, a phenomenon where Cooper pairs tunnel through a thin barrier between two superconductors, behaving like a single quantum mechanical entity. The instructor explains the physical observable quantum phase and the gauge-invariant phase gradient across a Josephson Junction, emphasizing that the supercurrent is independent of the mathematical description. Different types of Josephson Junctions are discussed, including SIS, SNS, and SCS. Real Josephson Junction examples are presented, such as thin film deposited AT/ALO/Al Josephson Junction. The lecture concludes with a recap on the DC and AC Josephson effects and the dominant types of Josephson Junctions.