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 an unbiased junction have been found for the first time. These effects are of interest for considerations of developing large-scale integrated superconducting circuits.