Chaotic dynamics of underdamped Josephson junctions in a ratchet potential driven by a quasiperiodic external modulation

In this article the classical dynamics of the underdamped Josephson junction in a periodic asymmetric potential of the ratchet type are considered. Driving the junction by an external quasiperiodic dual-frequency field, and in dependence on parameter values we show that the system exhibits chaotic trajectories and attractors. We also identify four voltage reversals occurring, associated with the junction bifurcation to periodic behaviour. We argue that the junction favours a directed transport accompanied by the destruction of the supercurrent state at zero voltage. The role of the incommensurability of the field frequencies and asymmetry of the potential has been discussed.