New Applications

Major advances in the design and fabrication of ultra-high performance logic and memory circuits were recently reported by IBM research scientists. The devices operate on entirely different principles from the silicon transistor circuits used in all of today´s computers. The experimental circuits, made of Josephson junctions, switch in 50 to 100 picoseconds (trillionths of a second), and the memory cells have an access time of 7 nanoseconds (billionths of a second). Even more important than these high switching speeds, the Josephson circuits generate only microwatts of heat–thousands of times less than high-speed transistor circuits. This permits them to be packed very closely together, an essential quality since with such high switching speeds the time an electrical impulse takes to move from one circuit to the next becomes the major limitation on a computer´s speed. In 100 picoseconds, for example, an electrical signal moves about half an inch.