Browse Prior Art Database

Josephson Three Terminal Isolator

IP.com Disclosure Number: IPCOM000079054D
Original Publication Date: 1973-Apr-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 24K

Publishing Venue

IBM

Related People

Hamel, HC: AUTHOR

Abstract

Fixed bias Josephson tunneling gates are arranged so that appreciable supercurrent can flow only in one direction, and is virtually inhibited when flowing in the opposite direction (similar to a semiconducting diode). The circuit also prevents current from propagating into the wrong branch.

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Josephson Three Terminal Isolator

Fixed bias Josephson tunneling gates are arranged so that appreciable supercurrent can flow only in one direction, and is virtually inhibited when flowing in the opposite direction (similar to a semiconducting diode). The circuit also prevents current from propagating into the wrong branch.

The Josephson devices J1 and J2 are biased with a DC current I BIAS, so that supercurrent Ig1 and Ig2 propagate toward the node N, as shown in Fig. 1A. The operating characteristics are shown in Fig. 1B. These supercurrents Ig1 and Ig2 must satisfy the following constraints in order to conduct a supercurrent: -Ir < Ig1 < If -Ir < Ig2 < If.

If these limits are exceeded, the Josephson device is switched out of the superconductive state, thereby opening up the superconductive path so that a current signal entering at terminal A can be propagated out terminal C, without propagating out terminal B. Similarly, a signal can enter terminal B and propagate out terminal C and not propagate out terminal A.

This facilitates the interconnection of logic and other circuits by isolating signal sources that must be connected to the same outgoing lines. This situation occurs, for example, when dot logic or two alternate paths are connected to a current power supply.

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