Balanced comparator for RSFQ qubit readout

T. Ohki, A. Savin, Juha Hassel, Leif Grönberg, T. Karminskaya, A. Kidiyarova-Shevchenko

    Research output: Contribution to journalArticleScientificpeer-review

    6 Citations (Scopus)

    Abstract

    The balanced comparator is an essential part of RSFQ-based readout for superconducting qubits. In this paper we report measurements of the sensitivity of the balanced comparator fabricated in a specialized 30 A/cm2 process with 3.6 ìm critical currents and measured at 30-500 mK. At sampling frequency of 3.5 GHz the measured gray zone is ÄI = 104 nA. Due to electron overheating in the shunt resistors the effective noise temperature is 140 mK. The gray zone has a strong dependence on sampling frequency above 5 GHz due to over-clocking. Related measurements have been reported where cooling fins and reduced critical current density of 10 A/cm2 were used, and a quantum limited gray zone of 40 nA was achieved. This makes single shot readout possible for the phase, RF-SQUID and persistent current qubits. The readout speed is 30-50 ps, which is quite favorable for error correction schemes.
    Original languageEnglish
    Pages (from-to)128-131
    JournalIEEE Transactions on Applied Superconductivity
    Volume17
    Issue number2
    DOIs
    Publication statusPublished - 2007
    MoE publication typeA1 Journal article-refereed

    Fingerprint

    readout
    Sampling
    Fins (heat exchange)
    Critical currents
    SQUIDs
    critical current
    cooling fins
    Error correction
    sampling
    Resistors
    noise temperature
    shunts
    Cooling
    resistors
    shot
    Electrons
    current density
    sensitivity
    Temperature
    electrons

    Keywords

    • Balanced comparator
    • Qubit readout
    • RSFQ

    Cite this

    Ohki, T., Savin, A., Hassel, J., Grönberg, L., Karminskaya, T., & Kidiyarova-Shevchenko, A. (2007). Balanced comparator for RSFQ qubit readout. IEEE Transactions on Applied Superconductivity, 17(2), 128-131. https://doi.org/10.1109/TASC.2007.897319
    Ohki, T. ; Savin, A. ; Hassel, Juha ; Grönberg, Leif ; Karminskaya, T. ; Kidiyarova-Shevchenko, A. / Balanced comparator for RSFQ qubit readout. In: IEEE Transactions on Applied Superconductivity. 2007 ; Vol. 17, No. 2. pp. 128-131.
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    title = "Balanced comparator for RSFQ qubit readout",
    abstract = "The balanced comparator is an essential part of RSFQ-based readout for superconducting qubits. In this paper we report measurements of the sensitivity of the balanced comparator fabricated in a specialized 30 A/cm2 process with 3.6 {\`i}m critical currents and measured at 30-500 mK. At sampling frequency of 3.5 GHz the measured gray zone is {\"A}I = 104 nA. Due to electron overheating in the shunt resistors the effective noise temperature is 140 mK. The gray zone has a strong dependence on sampling frequency above 5 GHz due to over-clocking. Related measurements have been reported where cooling fins and reduced critical current density of 10 A/cm2 were used, and a quantum limited gray zone of 40 nA was achieved. This makes single shot readout possible for the phase, RF-SQUID and persistent current qubits. The readout speed is 30-50 ps, which is quite favorable for error correction schemes.",
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    Ohki, T, Savin, A, Hassel, J, Grönberg, L, Karminskaya, T & Kidiyarova-Shevchenko, A 2007, 'Balanced comparator for RSFQ qubit readout', IEEE Transactions on Applied Superconductivity, vol. 17, no. 2, pp. 128-131. https://doi.org/10.1109/TASC.2007.897319

    Balanced comparator for RSFQ qubit readout. / Ohki, T.; Savin, A.; Hassel, Juha; Grönberg, Leif; Karminskaya, T.; Kidiyarova-Shevchenko, A.

    In: IEEE Transactions on Applied Superconductivity, Vol. 17, No. 2, 2007, p. 128-131.

    Research output: Contribution to journalArticleScientificpeer-review

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    AU - Savin, A.

    AU - Hassel, Juha

    AU - Grönberg, Leif

    AU - Karminskaya, T.

    AU - Kidiyarova-Shevchenko, A.

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    AB - The balanced comparator is an essential part of RSFQ-based readout for superconducting qubits. In this paper we report measurements of the sensitivity of the balanced comparator fabricated in a specialized 30 A/cm2 process with 3.6 ìm critical currents and measured at 30-500 mK. At sampling frequency of 3.5 GHz the measured gray zone is ÄI = 104 nA. Due to electron overheating in the shunt resistors the effective noise temperature is 140 mK. The gray zone has a strong dependence on sampling frequency above 5 GHz due to over-clocking. Related measurements have been reported where cooling fins and reduced critical current density of 10 A/cm2 were used, and a quantum limited gray zone of 40 nA was achieved. This makes single shot readout possible for the phase, RF-SQUID and persistent current qubits. The readout speed is 30-50 ps, which is quite favorable for error correction schemes.

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