MILLIOHM RESISTOR FOR RQL CIRCUITS
First Claim
1. A resistor comprising:
- a first terminal made of a superconducting metal;
a second terminal made of a superconducting metal; and
a Josephson junction device electrically connected between the first and second terminals, the Josephson junction device comprising ferromagnetic or antiferromagnetic material,wherein the resistor has a resistance value of between about one milliohm and about fifty milliohms.
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Accused Products
Abstract
A milliohm resistor is fabricated as a Josephson junction device that contains ferromagnetic or antiferromagnetic material of sufficient thickness to render the device entirely resistive between terminals. The device can have a resistance on the order of milliohms and can be consume a much smaller chip footprint than resistors of the same resistance fabricated using conventional resistive materials. Because the device can be fabricated without modification to processes used to fabricate reciprocal quantum logic (RQL) circuitry, it can easily be incorporated in RQL circuits to mitigate flux trapping or to perform other functions where very small resistances are needed. In particular, the device can burn off circulating currents induced by trapped flux without affecting the transmission of SFQ pulses through RQL circuitry.
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Citations
20 Claims
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1. A resistor comprising:
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a first terminal made of a superconducting metal; a second terminal made of a superconducting metal; and a Josephson junction device electrically connected between the first and second terminals, the Josephson junction device comprising ferromagnetic or antiferromagnetic material, wherein the resistor has a resistance value of between about one milliohm and about fifty milliohms. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A method of mitigating flux trapping in a reciprocal quantum logic (RQL) circuit, the method comprising:
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fabricating a resistor in an inductive loop in the RQL circuit, wherein the resistor has a resistance of between about one milliohm and about fifty milliohms, wherein the resistor has a footprint of less than twenty-five square micrometers, and wherein the resistor reduces to zero, in between about one millisecond and about ten microseconds, current circulating in the inductive loop as the result of trapped flux.
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18. A chip-fabricated device comprising:
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a first superconducting metal layer forming a first galvanic terminal; a second superconducting metal layer forming a second galvanic terminal; and between the superconducting metal layers, a barrier comprising one of; a synthetic antiferromagnet (SAF) comprising two ferromagnetic material layers separated by a spacer layer, the ferromagnetic material layers arranged to have antiparallel magnetizations with respect to each other, or an antiferromagnet layer; wherein the device has a resistance of between about one milliohm and about fifty milliohms, and wherein the device has a fabrication footprint of less than twenty-five square micrometers. - View Dependent Claims (19, 20)
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Specification