Rapid Single Quantum Flux (RFSQ) Logic
The main circuit components of RFSQ logic are based on overdamped Josephson junctions. They produce, store, transfer, and reproduce voltage pulses. These pulses are of picosecond duration. They have quantized area, which is correlated with the transmission of a single quantum of magnetic flux across a Josephson junction. According to superconductivity theory, the magnetic flux threading a superconducting loop or a hole in a bulk superconductor cannot acquire continuous values. It only assumes integral values which are multiples of a quantum of magnetic flux = h/(2q) where h stands for Plank’s constant and q is the elementary electronic charge. Its value is 2.0678 × 10−15 Wb = 2.07 mV ps. The RFSQ elements represent an ultrafast digital electronics technology working at 100–700 GHz, and beyond. Although it is consuming very low power, a disadvantage of this technology is the need of liquid helium environment, which is expensive even for military applications.
KeywordsMagnetic Flux Voltage Pulse Josephson Junction Clock Period Superconducting Quantum Interference Device
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