interference

One of the Powerful applications of Josephson junction is that leads to invention of SQUID. When two Josephson junctions are coupled together parallel in the presence of DC magnetic field will result in maximum super current to show interference effect as a function of magnetic field intensity. The Interference occurs due to the tunneling cooper electrons form both the end of the junction say J₁ and J₂ and corresponding current say I₁ and I₂ respectively. One can imagine this interference of electrons analogous with the quantum interference of light in the double slit experiment. The total supercurrent I₁ and I₂ are not in phase when a small magnetic field is applied. As a result there exists interference between I₁ and I₂.