Planar Josephson tunnel junctions in an asymmetric magnetic field

We analyze the consequences resulting from the asymmetric boundary conditions imposed by a nonuniform external magnetic field at the extremities of a planar Josephson tunnel junction and predict a number of testable signatures. When the junction length L is smaller than its Josephson penetration depth lambda(j), static analytical calculations lead to a Fresnel-like magnetic diffraction pattern, rather than a Fraunhofer-like one typical of a uniform field. Numerical simulations allow to investigate intermediate length (L approximate to lambda(j)) and long (L > lambda(j)) junctions. We consider both uniform and delta-shaped bias distributions. We also speculate on the possibility of exploiting the unique static properties of this system for basic experiments and devices.