Ratchet potential for fluxons in Josephson-junction arrays

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