SFQ Logic

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Single flux quantum (SFQ) technology is a super high-speed and low-power logic circuit featuring operating frequencies beyond 100 GHz with an energy dissipation smaller than CMOS circuits by three orders of magnitude.

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SFQ logic was invented by Likharev et al. in the 1990s and performs its  switching operation using superconducting elements called Josephson junctions. The demonstration of a toggle flip-flop at 770 GHz is the fastest logic gate reported so far. This value is overwhelmingly higher in operating frequency when compared with not only CMOS but with every other logic circuit technology including other nano-devices. 

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Our research team is focused on exploiting the super high-speed and low-power consumption of SFQ circuits. Notably, we developed the world’s first microprocessor using superconducting elements in 2004.  After that, we developed an architecture suitable for SFQ, and succeeded in demonstrating the operation of an 8-bit SFQ microprocessor at 18.1 GHz operating frequency with 3.4 mW power consumption. 

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Now we are conducting research to improve the speed even further while reducing power consumption.