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Josephson Heat Switch As an Auxiliary Reset Device for Superconducting Loops

IP.com Disclosure Number: IPCOM000044417D
Original Publication Date: 1984-Dec-01
Included in the Prior Art Database: 2005-Feb-05
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Kadlec, J: AUTHOR

Abstract

A Josephson heat switch, as an auxiliary reset device for superconducting loops, removes the condition in which neither driver nor reset gates return to a superconducting state and even after subsequent powering down and up remain inoperational. This simple device removes this condition without the necessity of warming up the whole chip. A latch-up condition in SET-RESET superconducting loops may occur due to the faulty operation of the line or may be introduced in operational testing of the string of driver gates. One or more Josephson junctions 11 and a proximity resistor 12 that can be heated by the control current form Josephson heat switch 13, which is small and can easily be incorporated in a SET-RESET loop. Fig. 1 shows a cross-section with two Josephson junctions 11.

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Josephson Heat Switch As an Auxiliary Reset Device for Superconducting Loops

A Josephson heat switch, as an auxiliary reset device for superconducting loops, removes the condition in which neither driver nor reset gates return to a superconducting state and even after subsequent powering down and up remain inoperational. This simple device removes this condition without the necessity of warming up the whole chip. A latch-up condition in SET-RESET superconducting loops may occur due to the faulty operation of the line or may be introduced in operational testing of the string of driver gates. One or more Josephson junctions 11 and a proximity resistor 12 that can be heated by the control current form Josephson heat switch 13, which is small and can easily be incorporated in a SET-RESET loop. Fig. 1 shows a cross-section with two Josephson junctions
11. The critical currents of the Josephson junctions 11 must, of course, be higher than the maximum loop current. Fig. 2 shows a typical SET-RESET loop, including auxiliary reset heat switch 13, which is equivalent to Fig. 1. The SET- RESET loop is attached to driver string 14. After powering down the driver string 14 with the latched-up loop, this loop will contain a certain circulating rest current that may render one or both gates inoperational. In order to remove this fault, current is applied through the control resistor 12 of the heat switch; the junctions 11 turn normal. The normal resistance of junctions 11 (Fig....