Influence of the Josephson junction on the impedance and noise of a resistive superconductive quantum interference device

Robert Soulen, William Fogle, Jack Colwell, Joshua Cohn, Heikki Seppä

Research output: Contribution to journalArticleScientificpeer-review

3 Citations (Scopus)

Abstract

The impedance and noise of a resistive superconductive quantum interference device (R‐SQUID) have been measured as a function of the dc and rf currents applied to it. The Josephson junction was adjustable so that data were also taken for several values of the junction critical current. The results were compared with the predictions of a resistively shunted junction (RSJ) model which takes into account the influence of the Josephson junction on the impedance and noise. The agreement was found to be quite good and demonstrates that the noise in the circuit is well understood. Use of the R‐SQUID as a noise thermometer below 1 K is assessed in terms of corrections due to the RSJ model. It is demonstrated how the dc and rf currents may be adjusted so that the total noise of the R‐SQUID is reduced to within 0.1% of the Johnson noise generated by the resistor alone. Under these conditions, the R‐SQUID may be used as a noise thermometer to determine thermodynamic temperature to this inaccuracy from 6 to 700 mK.
Original languageEnglish
Pages (from-to)5241-5249
JournalJournal of Applied Physics
Volume74
Issue number8
Publication statusPublished - 1993
MoE publication typeA1 Journal article-refereed

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Josephson junctions
impedance
interference
thermometers
resistors
critical current
thermodynamics
predictions

Keywords

  • Josephson junction

Cite this

Soulen, Robert ; Fogle, William ; Colwell, Jack ; Cohn, Joshua ; Seppä, Heikki. / Influence of the Josephson junction on the impedance and noise of a resistive superconductive quantum interference device. In: Journal of Applied Physics. 1993 ; Vol. 74, No. 8. pp. 5241-5249.
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abstract = "The impedance and noise of a resistive superconductive quantum interference device (R‐SQUID) have been measured as a function of the dc and rf currents applied to it. The Josephson junction was adjustable so that data were also taken for several values of the junction critical current. The results were compared with the predictions of a resistively shunted junction (RSJ) model which takes into account the influence of the Josephson junction on the impedance and noise. The agreement was found to be quite good and demonstrates that the noise in the circuit is well understood. Use of the R‐SQUID as a noise thermometer below 1 K is assessed in terms of corrections due to the RSJ model. It is demonstrated how the dc and rf currents may be adjusted so that the total noise of the R‐SQUID is reduced to within 0.1{\%} of the Johnson noise generated by the resistor alone. Under these conditions, the R‐SQUID may be used as a noise thermometer to determine thermodynamic temperature to this inaccuracy from 6 to 700 mK.",
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Influence of the Josephson junction on the impedance and noise of a resistive superconductive quantum interference device. / Soulen, Robert; Fogle, William; Colwell, Jack; Cohn, Joshua; Seppä, Heikki.

In: Journal of Applied Physics, Vol. 74, No. 8, 1993, p. 5241-5249.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Influence of the Josephson junction on the impedance and noise of a resistive superconductive quantum interference device

AU - Soulen, Robert

AU - Fogle, William

AU - Colwell, Jack

AU - Cohn, Joshua

AU - Seppä, Heikki

PY - 1993

Y1 - 1993

N2 - The impedance and noise of a resistive superconductive quantum interference device (R‐SQUID) have been measured as a function of the dc and rf currents applied to it. The Josephson junction was adjustable so that data were also taken for several values of the junction critical current. The results were compared with the predictions of a resistively shunted junction (RSJ) model which takes into account the influence of the Josephson junction on the impedance and noise. The agreement was found to be quite good and demonstrates that the noise in the circuit is well understood. Use of the R‐SQUID as a noise thermometer below 1 K is assessed in terms of corrections due to the RSJ model. It is demonstrated how the dc and rf currents may be adjusted so that the total noise of the R‐SQUID is reduced to within 0.1% of the Johnson noise generated by the resistor alone. Under these conditions, the R‐SQUID may be used as a noise thermometer to determine thermodynamic temperature to this inaccuracy from 6 to 700 mK.

AB - The impedance and noise of a resistive superconductive quantum interference device (R‐SQUID) have been measured as a function of the dc and rf currents applied to it. The Josephson junction was adjustable so that data were also taken for several values of the junction critical current. The results were compared with the predictions of a resistively shunted junction (RSJ) model which takes into account the influence of the Josephson junction on the impedance and noise. The agreement was found to be quite good and demonstrates that the noise in the circuit is well understood. Use of the R‐SQUID as a noise thermometer below 1 K is assessed in terms of corrections due to the RSJ model. It is demonstrated how the dc and rf currents may be adjusted so that the total noise of the R‐SQUID is reduced to within 0.1% of the Johnson noise generated by the resistor alone. Under these conditions, the R‐SQUID may be used as a noise thermometer to determine thermodynamic temperature to this inaccuracy from 6 to 700 mK.

KW - Josephson junction

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JO - Journal of Applied Physics

JF - Journal of Applied Physics

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