Josephson junction

In physics, a Josephson junction is a nonlinear, dissipationless circuit element that uses the Josephson effect in superconductors to form a nonlinear inductor. It consists of a weak barrier (such as an insulator) separating two superconductors. Pairs of electrons tunnel through the barrier, producing an effective inductance that is dependent on the phase difference between the superconductors.

The Josephson junction is used as a circuit element in superconducting loops. In a circuit, the Josephson inductance and the junction capacitance can be used to form a nonlinear oscillator, similar to a LC circuit, with a current-dependent inductance. Circuits with Josephson junctions are used to make superconducting magnetometers known as SQUIDs, in classical logic gates for ultrafast computing, and in circuit quantum electrodynamics to create superconducting qubits.