Rapid Single Quantum Flux (RFSQ) Logic

Part of the NanoScience and Technology book series (NANO)


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.


Magnetic Flux Voltage Pulse Josephson Junction Clock Period Superconducting Quantum Interference Device 


  1. 1.
    Mukhanov OA, Polonsky SV, Sevenov VK (1991) New elements of the RFSQ logic family. IEEE Trans Magn 27(2):2435–2438CrossRefGoogle Scholar
  2. 2.
    Likharev KK, Semenov VK (1991) RFSQ logic/memory family: a new Josephson junction technology for sub-tera-hertz-clock-frequency digital systems. IEEE Trans Appl Supercond 1(1):3–28CrossRefGoogle Scholar
  3. 3.
    Likharev KK (2016) Rapid single-flux-quantum logic. http://www.physics.sunysb.edu/Physics/RSFQ/Projects/WhatIs/rsfqre2m.html. Accessed 6 April 2016
  4. 4.
    Massachusetts Institute of Technology Lincoln Laboratory (2016) Forecasting superconductive electronics technology. The Next Wave 20(3). https://www.nsa.gov/research/tnw/tnw203/article2.shtml. Accessed 7 April 2016

Copyright information

© Springer India 2016

Authors and Affiliations

  1. 1.MEMS and Microsensors GroupCSIR-Central Electronics Engineering Research InstitutePilaniIndia

Personalised recommendations