JOSEPHSON-JUNCTION LADDERS - GROUND-STATE AND RELAXATION PHENOMENA

This paper considers a Josephson junction array with the geometry of a ladder and anisotropy in the Josephson couplings. The ground-state problem for the ladder corresponds to the one-for the one-dimensional chiral XY model in a twofold anisotropy field, which allows for a rigorous characterization of the ground-state phase diagram and the relevant elementary excitations for the system. The approach to equilibrium, which we study using Langevin dynamics, shows slow relaxation, typical of systems whose energy landscape in the configuration, space consists of a wealth of metastable states, dynamically disconnected.