Macroscopic quantum tunneling and phase diffusion in a La${}_{2-x}$Sr${}_x$CuO${}_4$ intrinsic Josephson junction stack

Abstract

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 $T^{\ast }\approx 2$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.

9 pages, 7 figures