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Josephson Circuit with Reduced Punchthrough

IP.com Disclosure Number: IPCOM000050411D
Original Publication Date: 1982-Oct-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 2 page(s) / 53K

Publishing Venue

IBM

Related People

Anderson, CJ: AUTHOR [+5]

Abstract

In Josephson circuitry, the phenomenon of punchthrough is known, wherein Josephson devices fail to reset when the AC power waveform changes polarity. In order to reduce the probability of punchthrough, it is proposed to apply a small control current to the Josephson device while the device is expected to reset.

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Josephson Circuit with Reduced Punchthrough

In Josephson circuitry, the phenomenon of punchthrough is known, wherein Josephson devices fail to reset when the AC power waveform changes polarity. In order to reduce the probability of punchthrough, it is proposed to apply a small control current to the Josephson device while the device is expected to reset.

The small control current is not in excess of about 10 percent of the nominal control current. Figs. 1 and 2 illustrate two techniques for applying this additional control current. In Fig. 1, a three-junction interferometer is comprised of the junctions J1, J2, and J3. AC power is applied at terminal 10, and the output of interferometer I is taken across the load resistor R(L). To provide an additional control current, a fraction of the gate current I(g) is asymmetrically fed into the interferometer at terminal A.

In Fig. 2, interferometer I is also comprised of three Josephson junctions J1, J2, and J3. AC power is supplied at terminal 12, and gate current I(g) flows into the interferometer. In the approach of Fig. 2, a fraction of the output current is magnetically coupled into the interferometer through the path including R(S). One could take the alternative approach of replacing R(S) with R(L), which couples all of the output current. In another alternative approach to that shown in Figs. 1 and 2, the value of the damping resistor R(D) could be changed. This would allow the internal modes of oscillation of the...