Periodic regimes and phase locking in the rf SQUID

TheI–V characteristic of the rf SQUID in the region of the first plateau is studied in the framework of the RSJ model of the Josephson junction. Periodic orbits with periods equal to integer multiples of the bias current period have been found. The given period is constant within a small interval of the bias current amplitude. The consequences of such phase locking on theI–V characteristic are discussed.