Evaluation of current sensitivity of quantum flux parametron

Yamanashi, Yuki; Matsushima, Takashi; Takeuchi, Naoki; Yoshikawa, Nobuyuki; Ortlepp, Thomas

doi:10.1088/1361-6668/aa73be

Cited by 11 publications

(10 citation statements)

References 27 publications

(40 reference statements)

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“…This is because this influence is believed to be dominant in the low-frequency operating regions. Moreover, analog circuit simulations considering only the thermal noise indicate that the measured gray zone width of the QFP operating at low-frequency regions is larger than that of the simulated result [16]. The gray zone width of the QFP in the low-frequency operating region might be determined not only by thermal noises, but also by the influence of the 1/f noise on the SFQ circuit operation, as stated in [22].…”

Section: Introductionmentioning

confidence: 87%

“…Because the superconducting circuits comprising superconducting quantum interference (SQUID) loops have a high sensitivity to a magnetic flux or currents, the operation speed and stability are limited by the noises in the circuit. The influence of the thermal noise at 4.2 K on the SFQ and QFP circuit operations has been numerically and experimentally studied [11][12][13][14][15][16]. The influence of 1/f noise, which is believed to be caused by the trapping of quasi-particles in the defects of the superconducting film [17], on the high-temperature superconductor Manuscript receipt and acceptance dates will be inserted here.…”

Section: Introductionmentioning

confidence: 99%

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Investigation of the Effects of 1/fNoise on Superconducting Circuits

Tsuna

Yamanashi

Yoshikawa

2020

IEEE Trans. Appl. Supercond.

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We analyzed the influence of 1/f noise in superconducting circuits on circuit operation using an analog circuit simulation. We devised a circuit simulation considering the 1/f noise using a conventional analog circuit simulator that can analyze the influence of thermal noises. In the circuit simulation, we used a passive filter that has a transfer function of -3 dB/oct to convert the Gaussian distributed white noise into the 1/f noise. We analyzed the gray zone characteristics of both the QFP and a singleflux-quantum current comparator considering both thermal and 1/f noises; the calculated gray zone width characteristics agree well with experimental results. Moreover, the influence of the 1/f noise is dominant in low operating speed regions for the QFP. These results indicate that the influence of the 1/f noise should be carefully considered to design superconducting circuits driven by a low-frequency clock.

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Section: Introductionmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 99%

Investigation of the Effects of 1/fNoise on Superconducting Circuits

Tsuna

Yamanashi

Yoshikawa

2020

IEEE Trans. Appl. Supercond.

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“…2(a), Iin is correctly sampled and digitized in synchronization with Ix. Without thermal fluctuation, the comparator can digitize an arbitrarily small Iin, but, in practice, the sensitivity of the comparator is limited by thermal noise [16]. Figure 2(b) shows the simulation results for the probability of switching to a logical value of 1 (P1) as a function of Iin for fs = 100 MHz and T = 4.2 K, where T is the operating temperature.…”

Section: Conventional Comparatormentioning

confidence: 99%

“…In addition, AQFP gates have high sensitivity owing to adiabatic switching [14,15], where the logic state can be switched with an input current slightly tilting the potential energy. We demonstrated an AQFP comparator with a sensitivity of approximately 1 μA [16], which is small enough to digitize the signal current from an NbTiN SSPD (~10 μA). In fact, we have successfully demonstrated NbTiN SSPDs using AQFP circuits [17,18], which digitize and encode the signal currents from the SSPDs in a cryocooler in order to reduce the number of coaxial cables required for reading out the SSPDs.…”

Section: Introductionmentioning

confidence: 99%

An Adiabatic Superconductor Comparator With 46 nA Sensitivity

Takeuchi

Yamae

Suzuki

et al. 2021

IEEE Trans. Appl. Supercond.

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Adiabatic quantum-flux-parametron (AQFP) circuits can operate with extremely small energy dissipation (~1 zJ per junction at 5 GHz) and high sensitivity (~1 μA) owing to adiabatic switching. Thus, AQFP logic is suitable to use as readout interfaces for cryogenic detectors, such as superconducting nanowire single-photon detectors (SSPDs). In order to extend the application of AQFP logic to various detectors, it is crucial to achieve even better sensitivity because some detectors, such as WSi SSPDs and transition edge sensors (TESs), require sub-μA sensitivity. In the present study, we propose a high-sensitivity AQFP comparator with a current transformer (CT), which increases the equivalent input current and thereby improves the sensitivity. Numerical simulation shows that the proposed comparator achieves a sensitivity approximately six times better than that of a conventional AQFP comparator. Furthermore, we demonstrate a sensitivity of 46 nA at 4.2 K for a sampling frequency of 500 Hz in the experiment.

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“…By averaging the output signals from the AQFP with an analog or digital integrator, its sensitivity is expected to be considerably improved. The AQFP gate has a reported sensitivity of a few μA in the GHz operation frequency range at 4.2 K [27]. There is a possibility that the sensitivity is improved at a lower temperature.…”

Section: Quantum Computing System Controlled By Superconducting Electmentioning

confidence: 99%

Superconducting Digital Electronics for Controlling Quantum Computing Systems

Yoshikawa

2019

IEICE Trans. Electron.

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The recent rapid increase in the scale of superconducting quantum computing systems greatly increases the demand for qubit control by digital circuits operating at qubit temperatures. In this paper, superconducting digital circuits, such as single-flux quantum and adiabatic quantum flux parametron circuits are described, that are promising candidates for this purpose. After estimating their energy consumption and speed, a conceptual overview of the superconducting electronics for controlling a multiple-qubit system is provided, as well as some of its component circuits. key words: qubit, quantum computing, single-flux quantum circuit, adiabatic quantum flux parametron circuit, superconducting integrated circuits Nobuyuki Yoshikawa received the B.E., M.E., and Ph.D. degrees in electrical and computer engineering from Yokohama National University, Japan, in 1984Japan, in , 1986Japan, in , and 1989, respectively. Since 1989, he has been with the Department of Electrical and Computer Engineering, Yokohama National University, where he is currently a Professor. His research interests include superconductive devices and their application in digital and analog circuits. He is also interested in single-electron-tunneling devices, quantum computing devices and cryo-CMOS devices. He is a member of

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Evaluation of current sensitivity of quantum flux parametron

Cited by 11 publications

References 27 publications

Investigation of the Effects of 1/fNoise on Superconducting Circuits

Investigation of the Effects of 1/fNoise on Superconducting Circuits

An Adiabatic Superconductor Comparator With 46 nA Sensitivity

Superconducting Digital Electronics for Controlling Quantum Computing Systems

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