Bifurcating, chaotic, and intermittent solutions in the rf-biased Josephson junction

Extensive numerical simulations of the rf-biased Josephson junction are presented. It is shown that, as the amplitude is increased for fixed damping and frequency, an apparently endless sequence of bifurcating-chaotic trees separated by periodic solutions exists. The state diagram characterized in the amplitude-damping plane at fixed frequency ($\Omega =0.65\mathrm{}$) shows a complex set of solutions. A detailed study of the transition in the high-damping limit is presented, indicating the bounds for asymmetric, bifurcating, and chaotic solutions for low ${\beta }_c$. It is shown that strange attractors are common to trapped and free-running chaotic solutions for nearby amplitudes due to intermittency among the various basins of attraction. Return maps at high amplitudes are found to be essentially one dimensional. Experimental consequences of our simulations are presented in terms of equivalent noise temperatures at low frequencies, resulting in maximum noise temperatures of the order of ${10}^6$-${10}^7$ K.