Wisconsin Alumni Research Foundation

L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des

James E Nordman

Jon S Martens

Gert K Hohenwarter

James B Beyer

Francois Colomb

Bernard Manhes

Philippe Cardinne

Raymond Serve

A superconducting active device has dual control inputs and is constructed such that the output of the device is effectively a linear mix of the two input signals. The device is formed of a film of superconducting material on a substrate and has two main conduction channels, each of which includes a weak link region. A first control line extends adjacent to the weak link region in the first channel and a second control line extends adjacent to the weak link region in the second channel. The current flowing from the first channel flows through an internal control line which is also adjacent to the weak link region of the second channel. The weak link regions comprise small links of superconductor, separated by voids, through which the current flows in each channel. Current passed through the control lines causes magnetic flux vortices which propagate across the weak link regions and control the resistance of these regions. The output of the device taken across the input to the main channels and the output of the second main channel and the internal control line will constitute essentially a linear mix of the two input signals imposed on the two control lines. The device is especially suited to microwave applications since it has very low input capacitance, and is well suited to being formed of high temperature superconducting materials since all of the structures may be formed coplanar with one another on a substrate.

Dual control active superconductive devices

Active superconducting devices are formed of thin films of superconductor which include a main conduction channel which has an active weak link region. The weak link region is composed of an array of links of thin film superconductor spaced from one another by voids and selected in size and thickness such that magnetic flux can propagate across the weak link region when it is superconducting. Magnetic flux applied to the weak link region will propagate across the array of links causing localized loss of superconductivity in the links and changing the effective resistance across the links. The magnetic flux can be applied from a control line formed of a superconducting film deposited coplanar with the main conduction channel and weak link region on a substrate. The devices can be formed of any type to superconductor but are particularly well suited to the high temperature superconductors since the devices can be entirely formed from coplanar films with no overlying regions. The devices can be utilized for a variety of electrical components, including switching circuits, amplifiers, oscillators and modulators, and are well suited to microwave frequency applications.

Active superconducting devices formed of thin films

A Josephson junction comprises a cylindrical substrate having a flat end face disposed in a plane perpendicular to the axis of the cylinder. At least two bodies of superconducting material such as niobium, tantalum or vanadium are carried by the substrate and have boundary surfaces disposed in that plane. Insulating material and semiconductor material spaces apart the superconductors; and electrical supply means extend lengthwise of the cylinder to bring electric current to that plane. In one embodiment, the superconductors are disposed on opposite sides of the plane; while in another embodiment, they are all disposed on the same side of the plane.

Josephson junction

Growing community of inventors

Madison, WI, United States of America

James E Nordman