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Damping Elements in Josephson Devices

IP.com Disclosure Number: IPCOM000077171D
Original Publication Date: 1972-Jun-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Zappe, HH: AUTHOR

Abstract

Josephson devices in which current is steered from one superconductive loop into another are essentially composed of a tuned parallel circuit containing the junction capacitance C(j), the nonlinear junction resistance R(j), and the self-inductance of the loops L. To increase the speed of the circuit for a given junction size, the value of L must be decreased. However, the critical resistance R(c) necessary to keep the circuit properly damped decreases as R(c) = square root of L/4C(j). At very high speeds (small L) these Josephson devices will be oscillatory when R(c)

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Damping Elements in Josephson Devices

Josephson devices in which current is steered from one superconductive loop into another are essentially composed of a tuned parallel circuit containing the junction capacitance C(j), the nonlinear junction resistance R(j), and the self- inductance of the loops L. To increase the speed of the circuit for a given junction size, the value of L must be decreased. However, the critical resistance R(c) necessary to keep the circuit properly damped decreases as R(c) = square root of L/4C(j). At very high speeds (small L) these Josephson devices will be oscillatory when R(c) <R(j).

To enable high-speed operation of Josephson device circuits without oscillation, a parallel resistor is added to the tunnel junction of each circuit. One way to do this is to cover the finished junction with a thin-metal layer. In addition, a thin-film resistor can be connected to the junction as long as this resistor stays in the immediate vicinity of the junction.

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