| Project/Area Number |
20K22412
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| Research Category |
Grant-in-Aid for Research Activity Start-up
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| Allocation Type | Multi-year Fund |
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| Review Section |
0302:Electrical and electronic engineering and related fields
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| Research Institution | Nagoya University |
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Principal Investigator |
Li Feng 名古屋大学, 工学研究科, 研究員 (00888381)
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| Project Period (FY) |
2020-09-11 – 2022-03-31
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| Project Status |
Completed (Fiscal Year 2021)
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| Budget Amount *help |
¥2,860,000 (Direct Cost: ¥2,200,000、Indirect Cost: ¥660,000)
Fiscal Year 2021: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Fiscal Year 2020: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
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| Keywords | Half-flux-quantum / balanced comparator / π-π-π SQUIDs / quantum fluctuation / random number generator / superconducting circuits / Half-Flux-Quantum / Random Number Generator / Comparator / Quantum Fluctuation / SQUID |
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| Outline of Research at the Start |
In this study, I propose a true random number generator (TRNG) based on the half-flux-quantum (HFQ) circuit, which can operate with quantum or thermal fluctuation. HFQ balanced comparator is composed of two identical serially connected π-π-π SQUIDs. The gray zone defined as the width of switching probability of HFQ comparator will reflect the effect of quantum or thermal fluctuation. I will measure the temperature- and energy-dependence of the gray zones and take autocorrelation of output signals for evaluating the randomness of the TRNGs with the NIST SP 800-22 statistical test suite.
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| Outline of Final Research Achievements |
To demonstrate a true random number generator (TRNG) based on quantum fluctuation,an novel Half-flux-quantum (HFQ) balanced comparater composed of π-π-π SQUIDs was proposed as TRNG. The nominal critical current of π-π-π SQUIDs can be reduced to 100 nA, which means the HFQ circuit can operate in the quantum regime at 10 mK stage.
In this study,the properties of SFIS (Nb/NiPd/Al-AlOx/Nb)π-JJs were characterized with temperature dependence. The intrinsic π phase shift can still be mentained at 10 mK stage and the critical current density is only slightly increased, which is important for HFQ circuits. The correct operation of HFQ TFF was measured up to 6.7 GHz and the un-shunted conventional single-flux-quantum (SFQ) circuits with SFQ/DC converts based on π-JJs were demonstrate at 4 K. These result set the foundation for demonstration of a HFQ circuit based TRNG that operating with quantum fluctuation or the control and readout circuits for Qubit at 10 mK.
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| Academic Significance and Societal Importance of the Research Achievements |
This research develope a new fabrication process for crygenic logical circuit, whose power consumption is extremely low, and can be used as the control or readout circuits of Qubits. The proposed TRNG operating with quantum fluctuation is an important element for future highly secure systems.
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