The
superconducting tunnel junction (STJ) — also known as a
superconductor–insulator–superconductor tunnel junction (SIS) — is an
electronic device consisting of two
superconductors separated by a very thin layer of
insulating material. Current passes through the junction via the process of
quantum tunneling. The STJ is a type of
Josephson junction, though not all the properties of the STJ are described by the Josephson effect.