Four-quadrant flux quanta counting for wide-range SQUID amplifiers

Mikko Kiviranta (Corresponding Author), Nikolay Beev

Research output: Contribution to journalArticleScientificpeer-review

3 Citations (Scopus)

Abstract

We have studied flux quanta counting in an open loop as a way to implement superconducting quantum interference device (SQUID) amplifiers with a large dynamic range and small power dissipation simultaneously. Good signal-to-noise ratio at all flux values is provided by using two SQUIDs, one yielding sin(Φ) and the other cos(Φ) proportional signals. In principle, the lack of feedback lifts the slew rate limitation due to the loop causality present in previously implemented flux quanta counters. Experimental results are shown for up to 180 Φ0 peak-to-peak flux ranges with a 1.5 μΦ0 Hz−1/2 noise floor, dominated by the digitizer noise. The SQUID and low-noise amplifier would allow a 0.07 μΦ0 Hz−1/2 noise floor with a more silent digitizer. Operation up to a 13 Φ0 μs−1 slew rate was demonstrated, but this is not a fundamental limitation. In our experiment, the mismatch between the sin(Φ) and cos(Φ) channels limited the practically achievable slew rate.
Original languageEnglish
Number of pages5
JournalSuperconductor Science and Technology
Volume27
Issue number7
DOIs
Publication statusPublished - 2014
MoE publication typeA1 Journal article-refereed

Fingerprint

quadrants
SQUIDs
counting
amplifiers
Fluxes
interference
analog to digital converters
quantum counters
Low noise amplifiers
low noise
dynamic range
Energy dissipation
Signal to noise ratio
signal to noise ratios
dissipation
Feedback
Experiments

Keywords

  • dynamic range
  • fluxon counting
  • SQUIDs
  • superconductivity

Cite this

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title = "Four-quadrant flux quanta counting for wide-range SQUID amplifiers",
abstract = "We have studied flux quanta counting in an open loop as a way to implement superconducting quantum interference device (SQUID) amplifiers with a large dynamic range and small power dissipation simultaneously. Good signal-to-noise ratio at all flux values is provided by using two SQUIDs, one yielding sin(Φ) and the other cos(Φ) proportional signals. In principle, the lack of feedback lifts the slew rate limitation due to the loop causality present in previously implemented flux quanta counters. Experimental results are shown for up to 180 Φ0 peak-to-peak flux ranges with a 1.5 μΦ0 Hz−1/2 noise floor, dominated by the digitizer noise. The SQUID and low-noise amplifier would allow a 0.07 μΦ0 Hz−1/2 noise floor with a more silent digitizer. Operation up to a 13 Φ0 μs−1 slew rate was demonstrated, but this is not a fundamental limitation. In our experiment, the mismatch between the sin(Φ) and cos(Φ) channels limited the practically achievable slew rate.",
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author = "Mikko Kiviranta and Nikolay Beev",
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Four-quadrant flux quanta counting for wide-range SQUID amplifiers. / Kiviranta, Mikko (Corresponding Author); Beev, Nikolay.

In: Superconductor Science and Technology, Vol. 27, No. 7, 2014.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Four-quadrant flux quanta counting for wide-range SQUID amplifiers

AU - Kiviranta, Mikko

AU - Beev, Nikolay

PY - 2014

Y1 - 2014

N2 - We have studied flux quanta counting in an open loop as a way to implement superconducting quantum interference device (SQUID) amplifiers with a large dynamic range and small power dissipation simultaneously. Good signal-to-noise ratio at all flux values is provided by using two SQUIDs, one yielding sin(Φ) and the other cos(Φ) proportional signals. In principle, the lack of feedback lifts the slew rate limitation due to the loop causality present in previously implemented flux quanta counters. Experimental results are shown for up to 180 Φ0 peak-to-peak flux ranges with a 1.5 μΦ0 Hz−1/2 noise floor, dominated by the digitizer noise. The SQUID and low-noise amplifier would allow a 0.07 μΦ0 Hz−1/2 noise floor with a more silent digitizer. Operation up to a 13 Φ0 μs−1 slew rate was demonstrated, but this is not a fundamental limitation. In our experiment, the mismatch between the sin(Φ) and cos(Φ) channels limited the practically achievable slew rate.

AB - We have studied flux quanta counting in an open loop as a way to implement superconducting quantum interference device (SQUID) amplifiers with a large dynamic range and small power dissipation simultaneously. Good signal-to-noise ratio at all flux values is provided by using two SQUIDs, one yielding sin(Φ) and the other cos(Φ) proportional signals. In principle, the lack of feedback lifts the slew rate limitation due to the loop causality present in previously implemented flux quanta counters. Experimental results are shown for up to 180 Φ0 peak-to-peak flux ranges with a 1.5 μΦ0 Hz−1/2 noise floor, dominated by the digitizer noise. The SQUID and low-noise amplifier would allow a 0.07 μΦ0 Hz−1/2 noise floor with a more silent digitizer. Operation up to a 13 Φ0 μs−1 slew rate was demonstrated, but this is not a fundamental limitation. In our experiment, the mismatch between the sin(Φ) and cos(Φ) channels limited the practically achievable slew rate.

KW - dynamic range

KW - fluxon counting

KW - SQUIDs

KW - superconductivity

U2 - 10.1088/0953-2048/27/7/075005

DO - 10.1088/0953-2048/27/7/075005

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JO - Superconductor Science and Technology

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SN - 0953-2048

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