Macroscopic quantum tunneling and phase diffusion in a   La$_{2-x}$Sr$_x$CuO$_4$ intrinsic Josephson junction stack
  We performed measurements of switching current distribution in a submicron La$_{2-x}$Sr$_x$CuO$_4$ (LSCO) intrinsic Josephson junction (IJJ) stack in a wide temperature range. The escape rate saturates below approximately 2\,K, indicating that the escape event is dominated by a macroscopic quantum tunneling (MQT) process with a crossover temperature $T^{*}\approx2\,$K. We applied the theory of MQT for IJJ stacks, taking into account dissipation and the phase re-trapping effect in the LSCO IJJ stack. The theory is in good agreement with the experiment both in the MQT and in the thermal activation regimes. 
Yuimaru Kubo, A.O. Sboychakov, Franco Nori, Y. Takahide, S. Ueda, I.   Tanaka, A.T.M.N. Islam, and Y. Takano
cond-mat.supr-con