Answer 1—A Josephson junction is an electronic device created by placing two superconductors in close proximity with an extremely thin insulating (or at least nonsuperconducting) barrier in between. It has some unique characteristics arising from the fact that electrons can tunnel in Cooper pairs through the insulator. For example, an applied DC voltage (V) across the barrier produces an AC current at the frequency f = 2eV/h, where e is the elementary charge and h is Planck’s constant.

Josephson junctions can function as extremely high-speed, low-power logic switching devices. They were once seen as the next big technology for general-purpose computing, but the need for the low temperatures associated with superconductors has limited the commercialization of this technology except in certain narrow niche markets.

Contributor: David Tweed