Inverse ac Josephson effect in long junctions

Abstract
In highly hysteretic long Josephson junctions irradiated with microwaves the rf-induced current steps can cross the zero-current axis. The quantized voltage states arise from the phase locking of fluxon oscillations, which in rf-driven junctions can occur even with negative current bias. This phenomenon is interesting both for nonlinear dynamics and for application to the Josephson voltage standard.