James E Nordman

US Patent:

50197215, May 28, 1991

Filed:

Aug 18, 1989

Appl. No.:

7/395965

Inventors:

Jon S. Martens - Madison WI
James B. Beyer - Madison WI
James E. Nordman - Madison WI
Gert K. G. Hohenwarter - Madison WI

Assignee:

Wisconsin Alumni Research Foundation - Madison WI

International Classification:

H03K 338
H03K 1792

US Classification:

307306

Abstract:

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.

US Patent:

40094790, Feb 22, 1977

Filed:

Dec 21, 1973

Appl. No.:

5/427262

Inventors:

Philippe Cardinne - Grenoble, FR
Francois Colomb - Echirolles, FR
Bernard Manhes - Grenoble, FR
James Emery Nordman - Madison WI
Raymond Serve - Eybens, FR

Assignee:

L'Air Liquide, Societe Anonyme pour l'Etude et l'Exploitation des
Procedes Georges Claude - Paris

International Classification:

H01L 3922
H01L 2302

US Classification:

357 5

Abstract:

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.

US Patent:

52296555, Jul 20, 1993

Filed:

Dec 26, 1991

Appl. No.:

7/816395

Inventors:

Jon S. Martens - Albuquerque NM
James B. Beyer - Madison WI
James E. Nordman - Madison WI
Gert K. G. Hohenwarter - Madison WI

Assignee:

Wisconsin Alumni Research Foundation - Madison WI

International Classification:

H03K 338
H03K 1792
H03K 508
H01L 3922

US Classification:

307306

Abstract:

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.