Intrinsic and extrinsic d-wave effects in YBa2Cu3O7-delta grain boundary Josephson junctions: Implications for pi circuitry

We have investigated the properties of biepitaxial YBa2Cu3O7-delta grain boundary Josephson junctions, which appear to be characterized by low barrier transmission probabilities. Extrinsic and intrinsic d-wave effects are discussed within the framework of novel designs for pi-circuitry and qubits. The absence of spontaneous magnetization and of the consequent additional noise, in a wide range of experimental conditions, seems to be encouraging for designs of ``quiet'' devices.