Double resonance in the system of coupled Josephson junctions

The effect of $LC$ shunting on the phase dynamics of coupled Josephson junctions has been examined. It has been shown that additional $(rc)$ branches appear in the current-voltage characteristics of the junctions when the Josephson frequency $\omega_{\text{J}}$ is equal to the natural frequency of the formed resonance circuit $\omega_{rc}$. The effect of the parameters of the system on its characteristics has been studied. Double resonance has been revealed in the system at $\omega_{\text{J}}=\omega_{rc}=2\omega_{LPW}$, where $\omega_{LPW}$ is the frequency of a longitudinal plasma wave appearing under the parametric-resonance conditions. In this case, electric charge appears in superconducting layers in the interval of the bias current corresponding to the $rc$ branch. The charge magnitude is determined by the accuracy with which the double resonance condition is satisfied. The possibility of the experimental implementation of the effects under study has been estimated.