We report an experimental and theoretical study of the phase diffusion in small Josephson junctions under microwave irradiation. A peculiar enhancement of the phase diffusion by microwaves is observed. The enhancement manifests itself by a pronounced current peak in the current-voltage characteristics. The voltage position Vtop of the peak increases with the power P of microwave radiation as Vtop∝P, while its current amplitude weakly decreases with P. As the microwave frequency increases, the peak feature evolves into Shapiro steps with finite slope. Our theoretical analysis taking into account the enhancement of incoherent superconducting current by multi-photon absorption is in good agreement with experimental data.
@article{arxiv.cond-mat/0406710,
title = {Enhancement of Josephson phase diffusion by microwaves},
author = {Y. Koval and M. V. Fistul and A. V. Ustinov},
journal= {arXiv preprint arXiv:cond-mat/0406710},
year = {2009}
}