  We report measurements of switching-current distribution (SWCD) from a
phase-diffusion branch to a quasiparticle-tunneling branch as a function of
temperature in a cuprate-based intrinsic Josephson junction. Contrary to the
thermal-activation model, the width of the SWCD increases with decreasing
temperature, down to 1.5 K. Based on the multiple-retrapping model, we
quantitatively demonstrate that the quality factor of the junction in the
phase-diffusion regime determines the observed temperature dependence of the
SWCD.
