Ratchet potential for fluxons in Josephson-junction arrays

We propose a simple configuration of a one-dimensional parallel array of Josephson junctions in which the pinning potential for trapped fluxons lacks inversion symmetry (ratchet potential). This system can be modelised by a set of non-linear pendula with alternating lenghts and asymmetric harmonic couplings. We show, by molecular dynamics simulation, that fluxons behave as single particles in which the predictions for overdamped thermal ratchets can be easily verified.