Lecture 5 Josephson Effects

•Quasi-particle Tunneling

•Pair Tunneling and weak Links

•SIS Josephson Junctions

•Superconducting Quantum Interference Devices (SQUIDS)

Quasi-Particle Tunneling

Josephson effect

(see also hand-out)

In 1962 Josephson predicted Cooper-pairs can tunnel through a weak link at zero voltage difference. Current in junction (called Josephson junction – Jj) is then equal to:

21sin cJJ

Electrical current flows between two SC materials - even when they are separated by a non-SC or insulator. Electrons "tunnel" through this non-SC region, and SC current flows.

Superconducting Quantum Interference Devices-

SQUIDS