Chaos and Its Associated Oscillations in Josephson Circuits

This paper summarizes the chaotic phenomena and their associated oscillations produced in Josephson circuits from the view point of nonlinear oscillations. The computer analysis is carried out for the oscillations of two types of a Josephson element, one of which is a tunnel type and the other a bridge type. The Josephson circuits considered here are an rf-driven circuit, an autonomous oscillation circuit and a distributed parameter circuit. The results of analysis show that there are four types of oscillations, i.e. periodic, subharmonic, quasi- periodic and chaotic oscillations in the circuit with the tunnel type Josephson junctions, while the dominant oscillations in the bridge type Josephson junction circuit are the periodic and quasi-periodic oscillations and there are only few chaotic oscillations. In addition to these oscillations, some kinds of relaxation oscillations can be observed. The chaos and its associated oscillations are discussed in relationship with circuit parameters.