Superconducting computing
Superconducting logic refers to a new class of logic circuits that rely on the properties of semiconductors to create resistance-less wires and ultrafast switches that do not rely on conventional CMOS transistors. A CPU built with superconducting logic has the protential to be 10-100 times more energy efficient than convential CMOS logic.[1]
The extreme power efficency of Superconductoring logic over conventional CMOS makes superconducting logic an enabling techology for the exaflop computer, the next generation of computers. An exaflop computer built in cmos logic is estimated to consume some 500 megawatts power. Superconducting computer allows for great saving in power of 1/10 to 1/100th the same power required compared to CMOS.[2]
When Superconducting logic is chilled to a few degrees above absolute zero, this technology become and attractive option for ultrafast CPU's, where operating speeds are measured in picoseconds and operating frequencies approach 770 Ghz.[3]
Since the early 1990's the dominate technology for superconducting logic has been based on rapid single-flux quantum (RSFQ) logic, which relays bits of information in the form of short voltage pulses carried by tiny, speeding vortices of current. RSFQ has been used to build a number of specialized devices needed for high-throughput and numerically intensive applications, such as communications receivers and signal processing. But the design consumes too much power to be scaled up to processors that could compete with CMOS chips in high-end computers. To distribute current among gates, RSFQ relies on a network of bias resistors that can consume 10 times as much power as superconducting logic uses for computation.[4]