Digital logic circuits

Recent progress in Josephson digital logic circuits is described. It is noted that changing the junction material from a lead alloy to niobium has dramatically improved process reliability, and that high-speed, low-power operations have been demonstrated at large-scale integrated-circuit levels. The first Josephson microprocessor, operated at 770 MHz, verified the potential of Josephson devices for future digital elements. The possibilities of the ultrafast Josephson computer, previously shelved because of a number of problems, are being actively reconsidered. The performance anticipated for Josephson digital circuits using high-temperature superconducting materials is also discussed.<
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