Quantum phase diffusion in a small underdamped Nb/AlOx/Nb junction (∼ 0.4 μm2) is demonstrated in a wide temperature range of 25-140 mK where macroscopic quantum tunneling (MQT) is the dominant escape mechanism. We propose a two-step transition model to describe the switching process in which the escape rate out of the potential well and the transition rate from phase diffusion to the running state are considered. The transition rate extracted from the experimental switching current distribution follows the predicted Arrhenius law in the thermal regime but is greatly enhanced when MQT becomes dominant.
@article{arxiv.1101.2250,
title = {Quantum Phase Diffusion in a Small Underdamped Josephson Junction},
author = {H. F. Yu and X. B. Zhu and Z. H. Peng and Ye Tian and D. J. Cui and G. H. Chen and D. N. Zheng and X. N. Jing and Li Lu and S. P. Zhao and Siyuan Han},
journal= {arXiv preprint arXiv:1101.2250},
year = {2015}
}