Basic operations of the quantum flux parametron

Harada, Yutaka; Nakane, Hideaki; Miyamoto, Nobuo; Kawabe, U.; Goto, Eiichi; Soma, Takashi

doi:10.1109/tmag.1987.1065574

Cited by 59 publications

(13 citation statements)

References 6 publications

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“…Nonhysteretic Josephson junctions are used as ultrafast switches. There are three main types of SFQ logic developed to date: Rapid Single Flux Quantum (RSFQ) logic/memory family [78], [79] and its two new 'energy-efficient' versions -ERSFQ [80] and eSFQ [81] -differing from RSFQ only by the biasing schemes; Reciprocal Quantum Logic (RQL) [82]; and Quantum Flux Parametron (QFP) logic [83], [84] and its adiabatic (AQFP) implementation [85], [86].…”

Section: Fabrication and Scalability Of Sfq Circuitsmentioning

confidence: 99%

“…Among the superconducting digital technologies developed to date only AQFP circuits can be truly energy efficient. AQFP is the same QFP invented by E. Goto more than 30 years ago, see [83]- [84] and references therein, but operated in a slow (adiabatic) regime [85], [86]. Instead of using JJ switching to move fluxons, as in RSFQ and RQL, the information in QFP is encoded by a fluxon location in a double-well potential, in the left ("0") or the right ("1") well, and moved by adiabatically varying the shape of the potential, using ac bias currents.…”

Section: B Adiabatic Quantum Flux Parametron (Aqfp) Circuitsmentioning

confidence: 99%

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Superconductor digital electronics: Scalability and energy efficiency issues (Review Article)

Tolpygo¹

2016

Low Temperature Physics

172

115

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Abstract-Superconductor digital electronics using Josephson junctions as ultrafast switches and magnetic-flux encoding of information was proposed over 30 years ago as a sub-terahertz clock frequency alternative to semiconductor electronics based on complementary metal-oxide-semiconductor (CMOS) transistors. Recently, interest in developing superconductor electronics has been renewed due to a search for energy saving solutions in applications related to high-performance computing. The current state of superconductor electronics and fabrication processes are reviewed in order to evaluate whether this electronics is scalable to a very large scale integration (VLSI) required to achieve computation complexities comparable to CMOS processors. A fully planarized process at MIT Lincoln Laboratory, perhaps the most advanced process developed so far for superconductor electronics, is used as an example. The process has nine superconducting layers: eight Nb wiring layers with the minimum feature size of 350 nm, and a thin superconducting layer for making compact high-kineticinductance bias inductors. All circuit layers are fully planarized using chemical mechanical planarization (CMP) of SiO 2 interlayer dielectric. The physical limitations imposed on the circuit density by Josephson junctions, circuit inductors, shunt and bias resistors, etc., are discussed. Energy dissipation in superconducting circuits is also reviewed in order to estimate whether this technology, which requires cryogenic refrigeration, can be energy efficient. Fabrication process development required for increasing the density of superconductor digital circuits by a factor of ten and achieving densities above 10 7 Josephson junctions per cm 2 is described.

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Section: Fabrication and Scalability Of Sfq Circuitsmentioning

confidence: 99%

Section: B Adiabatic Quantum Flux Parametron (Aqfp) Circuitsmentioning

confidence: 99%

Superconductor digital electronics: Scalability and energy efficiency issues (Review Article)

Tolpygo¹

2016

Low Temperature Physics

172

115

View full text Add to dashboard Cite

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“…Superconducting logic devices are candidates for supercomputer applications due to their high operating frequency and ultralow energy consumption [ 6 , 7 , 8 , 9 , 10 ]. The conventional Josephson junction [ 11 , 12 ], in which the superconducting current flows due to the phase difference between two superconducting electrodes, is the basic element of superconducting circuits such as single-flux quantum logic (SFQ) [ 13 , 14 ], quantum flux parametron [ 15 , 16 ], reciprocal quantum logic [ 17 , 18 ], and adiabatic superconductor logic [ 19 ]. Single-quantum logic is the most developed one in application to supercomputing [ 20 , 21 ]; within its framework, weak ferromagnetic couplings in Josephson junctions [ 22 , 23 , 24 , 25 ] were proposed as the intrinsic phase shifters of the superconducting wave function.…”

Section: Introductionmentioning

confidence: 99%

Synthesis, Characterization, and Magnetoresistive Properties of the Epitaxial Pd0.96Fe0.04/VN/Pd0.92Fe0.08 Superconducting Spin-Valve Heterostructure

et al. 2020

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A thin-film superconductor(S)/ferromagnet(F) F1/S/F2-type Pd0.96Fe0.04(20 nm)/VN(30 nm)/Pd0.92Fe0.08(12 nm) heteroepitaxial structure was synthesized on (001)-oriented single-crystal MgO substrate utilizing a combination of the reactive magnetron sputtering and the molecular-beam epitaxy techniques in ultrahigh vacuum conditions. The reference VN film, Pd0.96Fe0.04/VN, and VN/Pd0.92Fe0.08 bilayers were grown in one run with the target sample. In-situ low-energy electron diffraction and ex-situ X-ray diffraction investigations approved that all the Pd1−xFex and VN layers in the series grew epitaxial in a cube-on-cube mode. Electric resistance measurements demonstrated sharp transitions to the superconducting state with the critical temperature reducing gradually from 7.7 to 5.4 K in the sequence of the VN film, Pd0.96Fe0.04/VN, VN/Pd0.92Fe0.08, and Pd0.96Fe0.04/VN/Pd0.92Fe0.08 heterostructures due to the superconductor/ferromagnet proximity effect. Transition width increased in the same sequence from 21 to 40 mK. Magnetoresistance studies of the trilayer Pd0.96Fe0.04/VN/Pd0.92Fe0.08 sample revealed a superconducting spin-valve effect upon switching between the parallel and antiparallel magnetic configurations, and anomalies associated with the magnetic moment reversals of the ferromagnetic Pd0.92Fe0.08 and Pd0.96Fe0.04 alloy layers. The moderate critical temperature suppression and manifestations of superconducting spin-valve properties make this kind of material promising for superconducting spintronics applications.

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“…11 However, at present, there exists no latch for AQFP logic, which is an essential component of digital computing systems. In the early study of QFP logic, 12 several latches were proposed, 13,14 but none were practical due to their operation principles. For example, the ring shift register 14 holds data by permanently propagating data in the ring of serially connected gates.…”

Section: Introductionmentioning

confidence: 99%

Novel latch for adiabatic quantum-flux-parametron logic

Takeuchi

Ortlepp

Yamanashi

et al. 2014

Journal of Applied Physics

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Measurement of 10 zJ energy dissipation of adiabatic quantum-flux-parametron logic using a superconducting resonator Appl. Phys. Lett. 102, 052602 (2013); 10.1063/1.4790276Rapid single-flux quantum logic using π-shifters A 3 bit single flux quantum shift register based on high-T c bicrystal Josephson junctions operating at 50 K We herein propose the quantum-flux-latch (QFL) as a novel latch for adiabatic quantum-fluxparametron (AQFP) logic. A QFL is very compact and compatible with AQFP logic gates and can be read out in one clock cycle. Simulation results revealed that the QFL operates at 5 GHz with wide parameter margins of more than 622%. The calculated energy dissipation was only $0.1 aJ/bit, which yields a small energy delay product of 20 aJÁps. We also designed shift registers using QFLs to demonstrate more complex circuits with QFLs. Finally, we experimentally demonstrated correct operations of the QFL and a 1-bit shift register (a D flip-flop). V C 2014 AIP Publishing LLC.

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Basic operations of the quantum flux parametron

Cited by 59 publications

References 6 publications

Superconductor digital electronics: Scalability and energy efficiency issues (Review Article)

Superconductor digital electronics: Scalability and energy efficiency issues (Review Article)

Synthesis, Characterization, and Magnetoresistive Properties of the Epitaxial Pd0.96Fe0.04/VN/Pd0.92Fe0.08 Superconducting Spin-Valve Heterostructure

Novel latch for adiabatic quantum-flux-parametron logic

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