course induce a magnetic field which can be detected experimentally. The magnetic flux passing through the loop will have the value from 0 to a half of magnetic flux quanta, i.e. from 0 to Φ0/2, depending on the value of inductance L. Technologies and physical principles Ferromagnetic Josephson junctions. Consider a Josephson junction with a ferromagnetic Josephson barrier, i.e. the multilayers Superconductor-Ferromagnet-Superconductor (SFS) or Superconductor-Insulator-Ferromagnet-Superconductor (SIFS). In such structures the superconducting order parameter inside the F-layer oscillates in the direction perpendicular to the junction plane. As a result, for certain thicknesses of the F-layer and temperatures, the order parameter may become +1 at one superconducting electrode and −1 at the other superconducting electrode. In this situation one gets a Josephson junction. Note that inside the F-layer the competition of different solutions takes place and the one with the lower energy wins out. Various ferromagnetic junctions have been fabricated: SFS junctions with weak ferromagnetic interlayers; SFS junctions with strong ferromagnetic interlayers, such as Co, Ni, PdFe and NiFe SIFS junctions; and S-Fi-S junctions. Josephson junctions with unconventional order parameter symmetry. Novel superconductors, notably high temperature cuprate superconductors, have an anisotropic superconducting order parameter which can change its sign depending on the direction. In particular, a so-called d-wave order parameter has a value of +1 if one looks along the crystal axis a and −1 if one looks along the crystal axis b. If one looks along the ab direction (45° between a and b) the order parameter vanishes. By making Josephson junctions between d-wave superconducting films with different orientations or between d-wave and conventional isotropic s-wave superconductors, one can get a phase shift of . Nowadays there are several realizations of Josephson junctions of this type: tri-crystal grain boundary Josephson junctions, tetra-crystal grain boundary Josephson junctions, d-wave/s-wave ramp zigzag JJs Josephson junctions, tilt-twist grain boundary Josephson junctions, p-wave based Josephson junctions. Superconductor-NormalMetal-Superconductor (SNS) Josephson junctions with non-equilibrium electron distribution in N-layer. Superconductor – quantum dot-superconductor (S-QuDot-S) Josephson junctions (implemented by carbon nanotube Josephson junctions). Historical developments Theoretically, the first time the possibility of creating a Josephson junction was discussed by Bulaevskii et al. , who considered a Josephson junction with paramagnetic scattering in the barrier. Almost one decade later, the possibility of having a Josephson junction was discussed in the context of heavy fermion p-wave superconductors. Experimentally, the first Josephson junction was a corner junction made of yttrium barium copper oxide