Electric current in a wire is like a crowd of people hurrying down a corridor. Usually, each person bumps into walls and loses speed almost instantly: that's electrical resistance. But in some materials, like a building with side halls, charge carriers can step into special 'pockets' (energy valleys) for a long time or retain energy after a push for a while. The time spent in such a pocket and the energy relaxation time can be hundreds of times longer than the time between collisions.

The authors considered a contact between two superconductors separated by such a 'leisurely' normal layer. It turned out that at a constant voltage, the current through the junction does not grow monotonically but climbs a hump twice: the first peak appears when the voltage manages to accelerate electrons before they lose energy, and the second when the voltage kicks them out of the pockets. These peaks can significantly exceed the usual critical current of the junction.

Practically, this means that such a junction can act as a tunable nonlinear element: at a fixed current it produces almost no voltage drop, but with the slightest change in conditions it switches abruptly. Such structures could be useful in ultra-sensitive magnetometry or in logic circuits where low power dissipation is important. The idea itself relies on a generalization of the Larkin–Ovchinnikov kinetic equations to the case of multi-valley superconductors — a mathematical tool that allowed the slow processes to be carefully accounted for.