Current-voltage characteristics of a four-terminal superconducting weak link

The current-voltage characteristics of a new type of Josephson-like junction consisting of four superconductors in connection with a common region via separate weak links are investigated. This arrangement permits strong interaction and proximity effects to occur inside the composite junction, and the observed variations in the I--V curves can be explained mainly in terms of an exchange of dc and ac quasiparticle currents between phase-slip centers. In particular, direct frequency locking among three Josephson oscillators and induced dc voltage in a unbiased junction have been found for the first time. These effects are of interest for considerations of developing large-scale integrated superconducting circuits