Macroscopic quantum tunneling in a d-wave high-Tc superconductor
  There is a wide recognition that Josephson-junction-like structures intrinsic to the layered cuprate high temperature superconductors offer an attractive stage for exploiting possible applications to new quantum technologies. On the other hand the low energy quasiparticle excitations characteristically present in these d-wave superconductors may easily destruct the coherence required. Here we demonstrate for the first time the feasibility of macroscopic quantum tunneling in the intrinsic Josephson junctions of a high temperature superconductor, and find it to be characterized by a high classic-to-quantum crossover temperature and a relatively weak quasiparticle dissipation. 
K. Inomata, S. Sato, K. Nakajima, A. Tanaka, Y. Takano, H. B. Wang, M.   Nagao, S. Kawabata and T. Hatano