Underlying physical aspects of fluctuations in YBa2Cu3O7−δ grain boundary Josephson junctions

High quality YBa2Cu3O7−δ biepitaxial grain boundary junctions allowed one of the first evidences of macroscopic quantum behavior and mesoscopic transport in high critical temperature superconductors (HTS) systems. Both these studies touch delicate issues on fluctuations and give important feedback on the understanding of coherent transport of quasiparticles and of the dissipation mechanisms in HTS.