Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

IEEJ Transactions on Fundamentals and Materials

Functional Switching in Quantum-Flux-Parametron with Ferromagnetic Patterns

Hiroshi T. ITO, Soya Taniguchi, Sota Kurokawa, Masamitsu Tanaka, Hiroyuki Akaike, Akira Fujimaki

Published Jan 1, 2016• 0 citations
Publisher

Abstract

Functional switching has been demonstrated based on quantum flux parametron (QFP) circuits with ferromagnetic patterns toward reconfigurable circuits. We form small ferromagnetic patterns of a PdNi alloy on a superconducting loop without degradation of superconductivity. Direction and strength of magnetization of ferromagnetic patterns are controlled by direction and magnitude of an applied magnetic field in a cooling process around the Currie points of the alloy. The ferromagnetic patterns induce a circulating current serving as one of the input currents in a three-inputs QFP majority gate. We obtained functional switching between the AND to the OR operation depending on the direction and strength of magnetization of the ferromagnetic patterns experimentally. The obtained operation margin agreed with a numerically obtained margin, though the magnitude of magnetization at the switching between two operation modes was different. This technique add new functionality and flexibility to the QFP-based integrated circuits.

DOI
10.1541/ieejfms.136.753

Related papers

Reconfigurable adiabatic quantum-flux-parametron with superconducting phase shift controlled by magnetic flux

Aoto Tanaoka, Nobuyuki Yoshikawa, Yuki Yamanashi

Abstract The adiabatic quantum-flux-parametron (AQFP), which can operate with ultra-low energy consumption, has attracted attention as an alternative to semiconductor circuits. The development of reconfigurable AQFP devices is essential for advancing AQFP integrated circuits. However, research on reconfigurable devices at the logic gate level remains limited. We propose an AQFP circuit capable of reconfiguring its logic function by controlling the superconducting phase shift through externally applied magnetic flux. In AQFP logic, logic ‘1’ and ‘0’ are represented by the polarity of the current. The proposed circuit can switch between the Buffer function, which propagates the input current with its polarity unchanged, and the NOT function, which propagates it with the polarity inverted. We analytically derived the parameter conditions for correct operation and determined the parameters within this range to achieve adiabatic operation and sufficient element margins for experimental demonstration. We fabricated the proposed reconfigurable circuit using the 10 kA cm −2 Nb four-layer superconducting circuit fabrication process, and experimentally confirmed correct operation for both the Buffer and NOT functions. The control current margins, which are responsible for the functional reconfiguration, were −2.3% to +31.2% for chip 1 and +0.8% to +35.1% for chip 2. Both margins had widths comparable to the simulation result. This work presents the first experimental demonstration of an AQFP circuit whose function can be reconfigured using only a control current. We believe this work will contribute to the advancement of reconfigurable AQFP devices.

Superconductor Science and Technology•Jul 1, 2026•0 citations

Quantum flux parametron

Y. Harada, Eiichi Goto Eiichi Goto, N. Miyamoto

The Quantum Flux Parametron (QFP) is a new cryogenic switching device based on the parametron principle and Josephson technology. Due to the magnetic flux quantization in superconducting devices, the switching mechanism of the QFP is quite different from that of semiconductors. This presentation describes the device characteristics. QFPs have been fabricated using the Nb/Pb-alloy Josephson junction process, and their basic operation is evaluated. Over 20dB current gain is attained. One-half frequency-divider operation up to 1.8GHz has been successfully observed.

Technical digest - International Electron Devices Meeting/Technical digest•Jan 1, 1987•10 citations

Quantum Flux Parametron

The Quantum Flux Parametron (QFP) is a new cryogenic switching device based on the parametron principle and Josephson technology. Due to the magnetic flux quantization in superconducting devices, the switching mechanism of the QFP is quite different from that of semiconductors. This presentation describes the device characteristics. QFPs have been fabricated using the Nb/Pb-alloy Josephson junction process, and their basic operation is evaluated. Over 20dB current gain is attained. One-half frequency-divider operation up to 1.8GHz has been successfully observed.

WORLD SCIENTIFIC eBooks•Mar 1, 1991•9 citations

Investigation Into the Individual Configuration of Superconducting Phase Shift Elements Made of Ferromagnetic Patterns for Reconfigurable Circuits

Shozo TANIGUCHI, Hiroshi T. ITO, Kouta Ishikawa +4 more

Reconfigurable superconducting phase shift elements (PSEs) provide high design flexibility in rapid single flux quantum (RSFQ) circuits. Small ferromagnetic patterns were placed on superconducting loops in an RSFQ circuit. The patterns serve as reconfigurable PSEs providing the direction and magnitude of magnetization can be controlled for each pattern individually. A two-dimensional wire mesh architecture was employed to allow for individual configuration and to reduce the number of wires required. Although opposing magnetic fields may occasionally be generated during half-selection using this architecture, experimentally obtained magnetization curves revealed that the orientation of the magnetic field was maintained. An RSFQ circuit, using a reconfigurable PSE, has been successfully demonstrated, potentially leading to large-scale reconfigurable RSFQ circuits

IEEE Transactions on Applied Superconductivity•Dec 20, 2016•5 citations

Design and fabrication of QFP logic gates based on YBa/sub 2/Cu/sub 3/O/sub 7/ step-edge junctions

H. Hasegawa, Y. Tarutani, Uki Kabasawa +3 more

Quantum Flux Parametron (QFP) logic gates were designed and fabricated from a single layer of YBa/sub 2/Cu/sub 3/O/sub 7/ thin film based on step-edge Josephson junctions. Self-inductance (L) of the QFP loop, an important circuit parameter, as is critical current (J/sub c/) of the Josephson junction, was determined by using directly coupled dc superconducting quantum interference devices (SQUIDs). Magnetically coupled dc SQUIDs were used to detect the output signal from the QFP. Simulated waveforms were used to identify the operation modes of the QFP as a function of the circuit parameters. From examination of the output waveforms of the QFP, operation in agreement with simulations was confirmed.

IEEE Transactions on Applied Superconductivity•Jun 1, 1997•4 citations

A new quantum flux parametron logic gate with large input margin

W. Hioe, M. Hosoya, Eiichi Goto

The quantum flux parametron (QFP) is a flux-transfer, flux-activated Josephson logic device which realizes much lower power dissipation than other Josephson logic devices. Being a two-terminal device, its correct operation may be affected by coupling to other QFPs. The problems include backcoupling form active QFPs through inactive QFPs (relay noise), coupling between QFPs activated at different times because of clock skew (homophase noise), and interaction between active QFPs (reaction hazard). Previous QFP circuits worked by wired-majority, which is a linear input logic and has low input margin. A logic gate (D-gate) using a QFP to perform logic operations has been analyzed and tested by computer simulation. Relay noise, homophase noise, and reaction hazard are substantially reduced. Moreover, the inputs have little interaction, and hence input margin is greatly improved. Using only D-gates it is possible to realize any combinational logic function. Important logic functions can be realized using one gate, such as a two-input multiplexer, majority, and parity. Since the QFP has a latching effect, D-gates can realize fully pipelined circuits without additional registers.

IEEE Transactions on Magnetics•Mar 1, 1991•8 citations
Functional switching has been demonstrated based on quantum flux parametron (QFP) circuits with ferromagnetic patterns toward reconfigurable circuits. We form small ferromagnetic patterns of a PdNi alloy on a superconducting loop without degradation of superconductivity. Direction and strength of magnetization of ferromagnetic patterns are controlled by direction and magnitude of an applied magnetic field in a cooling process around the Currie points of the alloy. The ferromagnetic patterns induce a circulating current serving as one of the input currents in a three-inputs QFP majority gate. We obtained functional switching between the AND to the OR operation depending on the direction and strength of magnetization of the ferromagnetic patterns experimentally. The obtained operation margin agreed with a numerically obtained margin, though the magnitude of magnetization at the switching between two operation modes was different. This technique add new functionality and flexibility to the QFP-based integrated circuits.
Abstract The adiabatic quantum-flux-parametron (AQFP), which can operate with ultra-low energy consumption, has attracted attention as an alternative to semiconductor circuits. The development of reconfigurable AQFP devices is essential for advancing AQFP integrated circuits. However, research on reconfigurable devices at the logic gate level remains limited. We propose an AQFP circuit capable of reconfiguring its logic function by controlling the superconducting phase shift through externally applied magnetic flux. In AQFP logic, logic ‘1’ and ‘0’ are represented by the polarity of the current. The proposed circuit can switch between the Buffer function, which propagates the input current with its polarity unchanged, and the NOT function, which propagates it with the polarity inverted. We analytically derived the parameter conditions for correct operation and determined the parameters within this range to achieve adiabatic operation and sufficient element margins for experimental demonstration. We fabricated the proposed reconfigurable circuit using the 10 kA cm −2 Nb four-layer superconducting circuit fabrication process, and experimentally confirmed correct operation for both the Buffer and NOT functions. The control current margins, which are responsible for the functional reconfiguration, were −2.3% to +31.2% for chip 1 and +0.8% to +35.1% for chip 2. Both margins had widths comparable to the simulation result. This work presents the first experimental demonstration of an AQFP circuit whose function can be reconfigured using only a control current. We believe this work will contribute to the advancement of reconfigurable AQFP devices.
The Quantum Flux Parametron (QFP) is a new cryogenic switching device based on the parametron principle and Josephson technology. Due to the magnetic flux quantization in superconducting devices, the switching mechanism of the QFP is quite different from that of semiconductors. This presentation describes the device characteristics. QFPs have been fabricated using the Nb/Pb-alloy Josephson junction process, and their basic operation is evaluated. Over 20dB current gain is attained. One-half frequency-divider operation up to 1.8GHz has been successfully observed.
The Quantum Flux Parametron (QFP) is a new cryogenic switching device based on the parametron principle and Josephson technology. Due to the magnetic flux quantization in superconducting devices, the switching mechanism of the QFP is quite different from that of semiconductors. This presentation describes the device characteristics. QFPs have been fabricated using the Nb/Pb-alloy Josephson junction process, and their basic operation is evaluated. Over 20dB current gain is attained. One-half frequency-divider operation up to 1.8GHz has been successfully observed.
Reconfigurable superconducting phase shift elements (PSEs) provide high design flexibility in rapid single flux quantum (RSFQ) circuits. Small ferromagnetic patterns were placed on superconducting loops in an RSFQ circuit. The patterns serve as reconfigurable PSEs providing the direction and magnitude of magnetization can be controlled for each pattern individually. A two-dimensional wire mesh architecture was employed to allow for individual configuration and to reduce the number of wires required. Although opposing magnetic fields may occasionally be generated during half-selection using this architecture, experimentally obtained magnetization curves revealed that the orientation of the magnetic field was maintained. An RSFQ circuit, using a reconfigurable PSE, has been successfully demonstrated, potentially leading to large-scale reconfigurable RSFQ circuits
Quantum Flux Parametron (QFP) logic gates were designed and fabricated from a single layer of YBa/sub 2/Cu/sub 3/O/sub 7/ thin film based on step-edge Josephson junctions. Self-inductance (L) of the QFP loop, an important circuit parameter, as is critical current (J/sub c/) of the Josephson junction, was determined by using directly coupled dc superconducting quantum interference devices (SQUIDs). Magnetically coupled dc SQUIDs were used to detect the output signal from the QFP. Simulated waveforms were used to identify the operation modes of the QFP as a function of the circuit parameters. From examination of the output waveforms of the QFP, operation in agreement with simulations was confirmed.
The quantum flux parametron (QFP) is a flux-transfer, flux-activated Josephson logic device which realizes much lower power dissipation than other Josephson logic devices. Being a two-terminal device, its correct operation may be affected by coupling to other QFPs. The problems include backcoupling form active QFPs through inactive QFPs (relay noise), coupling between QFPs activated at different times because of clock skew (homophase noise), and interaction between active QFPs (reaction hazard). Previous QFP circuits worked by wired-majority, which is a linear input logic and has low input margin. A logic gate (D-gate) using a QFP to perform logic operations has been analyzed and tested by computer simulation. Relay noise, homophase noise, and reaction hazard are substantially reduced. Moreover, the inputs have little interaction, and hence input margin is greatly improved. Using only D-gates it is possible to realize any combinational logic function. Important logic functions can be realized using one gate, such as a two-input multiplexer, majority, and parity. Since the QFP has a latching effect, D-gates can realize fully pipelined circuits without additional registers.