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Prevention of Gain Loss From Thin Electrode Effects

IP.com Disclosure Number: IPCOM000087639D
Original Publication Date: 1977-Feb-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Wolf, P: AUTHOR

Abstract

In Josephson junctions having M2 layers of a thickness of the order of the London penetration depth, screening currents in the M2 layer tend to cancel one another and, thus, require higher external fields to reach a certain point in the gain characteristics. This is avoided by obviating the field at the bottom of the M2 layer.

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Prevention of Gain Loss From Thin Electrode Effects

In Josephson junctions having M2 layers of a thickness of the order of the London penetration depth, screening currents in the M2 layer tend to cancel one another and, thus, require higher external fields to reach a certain point in the gain characteristics.

This is avoided by obviating the field at the bottom of the M2 layer.

One simple way is by removing the ground plane below the M2 layer. In order to provide a low-inductance path for return currents, the M2 may overlap the ground plane at the edges. If the low-inductance path is unimportant, the overlap may be omitted. In cases where galvanic isolation of junctions from the ground plane is not required, the ground plane may be used directly as the M2.

Another possibility is to bring the beginning and end of the M4 control windings closely together where they cross the edge of the M2 layer such that the current induced by the M4 on top of the M2 returns in the region where the beginning and end of the M4 are located. The distance of this location from the junction should be about 2...3 separations of the M4 windings when leaving the M2 layer.

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