Experimental critical current patterns in Josephson junction ladders

We present an experimental and theoretical study of the magnetic-field depe ndence of the critical current of Josephson junction ladders. At variance w ith the well-known case of a one-dimensional (1D) parallel array of Josephs on junctions the magnetic-field patterns display a single minimum even for very low values of the self-inductance parameter beta(L). Experiments perfo rmed changing both the geometrical value of the inductance and the critical current of the junctions show a good agreement with numerical simulations. We argue that the observed magnetic-field patterns are due to a peculiar m apping between the isotropic Josephson ladder and the 1D parallel array wit h the self-inductance parameter beta(L)(eff)=beta(L)+2.