Macroscopic Quantum Tunneling and Quasiparticle Dissipation in d-wave   Superconductor Josephson Junctions
  We examine the macroscopic quantum tunneling (MQT) in high-Tc superconductor Josephson junctions with a d-wave order parameter. Using microscopic Hamiltonian and the functional integral method, we analytically obtain the MQT rate (the inverse lifetime of the metastable state) for the c-axis twist Josephson junctions. In the case of the zero twist angle, the system shows the super-Ohmic dissipation due to the presence of the nodal quasiparticle tunneling. Therefore, the MQT rate is strongly suppressed in compared with the finite twist angle cases. 
Shiro Kawabata, Satoshi Kashiwaya, Yasuhiro Asano, and Yukio Tanaka