AQFP Logic

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Adiabatic quantum-flux-parametron (AQFP) logic is superconducting logic family that has extremely low power consumption. Eiichi Goto et al. proposed the original QFP circuit in the 1980s which is a superconducting Josephson junction version of his earlier invention known as the parametron that was used in early Japanese computers in the 1950s and 1960s. 

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From the 2010s, our laboratory optimized some of the parameters of the QFP by exploiting the availability of more advanced fabrication processes to make the most out of the QFP's key feature: low power consumption. Using state-of-the-art fabrication processes, we proposed an ultra energy-efficient QFP known as the adiabatic QFP (AQFP). It adopts a gradual switching behavior where the shape of its potential energy is changed adiabatically even at GHz operating speeds. 

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We conducted an actual measurement which shows the energy consumption per junction is 1.4 zJ (24 times as much as thermal energy at 4.2 K) in an AQFP adder operating at 5 GHz. Furthermore, we developed the first microprocessor using AQFPs, and successfully demonstrated its operation. 

 

Now we are conducting research to apply AQFP technology for various fields, such as microprocessors using AQFP circuits, superconducting photon detectors, interface circuits for quantum computers, reversible computers, and stochastic computers.