Small Josephson junction as detector of non-Gaussian noise

The current in a a Coulomb blockaded Josephson junction is sensitive to voltage or phase fluctuations in its electromagnetical environment. This property can be used to detect noise also from non-Gaussian noise sources. We have experimentally studied IV-curves of as a function of the shot noise current in a nearby tunnel junction. We observe a linear enhancement of zero-bias conductance of the Josephson junction as a function of the shot noise power. Furthermore, with increasing shot noise power, the IV-curves becomes asymmetric with a shift of minimum conductance and the appearance of a local conductance maximum. A quantitative explanation for the asymmetric features due to the non-Gaussian noise sources is still an open question. There is also motivation to pursue modifications of the current scheme in order to detect individual statistical moments of noise and to connect different noise sources to the Josephson junction. © 2005 American Institute of Physics.