Frustration-driven Josephson phase dynamics

The Josephson equations predict remarkable effects concerning the phase state\nof a superconducting junction with an oscillating current induced by a static\nvoltage. Whether the paradigm can be twisted by yielding an oscillating voltage\nwithout making use of harmonic drives is a fundamentally relevant problem yet\nnot fully settled. Here, we demonstrate that a dynamical regime with an\noscillating phase evolution is a general hallmark of driven Josephson systems\nexhibiting sign competition in the Josephson couplings. We show that in\nfrustrated Josephson systems an oscillating phase dynamics gets switched on by\ndriving the changeover among different ground states, which can be induced by\nvarying the parameters that set the phase state. Remarkably, the character of\nthe transitions in the Josephson phase space allows different types of\ndynamics, with few or several harmonics. This result sets out a characteristic\nmark of any superconducting system with frustrated Josephson couplings and can\nbe exploited to disentangle the complexity of the underlying phases.\n