Frontiers Problems of the Josephson Effect: From Macroscopic Quantum Phenomena Decay to High-T c Superconductivity

The macroscopic quantum decay phenomena occurring in Josephson structures represent one of the most intriguing issues of the weak coupling superconductivity, due to both fundamental physics implications and stimulating potential applications. In this chapter, the main aspects of the macroscopic quantum tunneling (MQT) are discussed for both low Tc and high Tc Josephson junctions. Particular attention will be dedicated to the latter for which the unconventional character of the order parameter plays a very important role. Both experimental and theoretical aspects are reviewed.