- Rapid single flux quantum
electronics, rapid single flux quantum (RSFQ) is a digitalelectronics technology that relies on quantum effects in superconductingmaterials to switch signals, instead of transistors. However, it is not a quantum computingtechnology in the traditional sense. Even so, RSFQ is very different from the traditional CMOS transistortechnology used in every day computers:
* It is based on
superconductors, so a cryogenicenvironment is required
* Instead of voltage levels, digital signals are represented by
picosecond-duration pulses that travel down superconducting microstrip transmission lines.
* The pulses are single
quantaat the lowest energy levelallowed by quantum mechanicsin the system, and hence cannot change significantly in transit. They do not lose energy, spread out, or interfere.
* The quantum pulses are switched by
Josephson junctions instead of transistors
* Unlike normal circuitry, signals cannot be split into multiple outputs without active circuit elements
Quantum flux parametron, a related digital logic technology.
* Interoperable with CMOS circuitry and infrared technology
* Extremely fast operating frequency (up to hundreds of
* Existing chip manufacturing technology can be adapted to manufacture RSFQ circuitry
* Good tolerance to manufacturing variations
* RSFQ circuitry is essentially
self clocking, making asynchronousdesigns much more practical.
cryogeniccooling; liquid heliummay be necessary unless high-temperature superconductors can be manufactured in this way,
* Signals cannot be split into multiple outputs without active circuit elements.
* Optical and other high-speed network switching devices
Digital signal processing, even up to radiofrequency signals.
* High speed
* [http://citeseer.ist.psu.edu/yerosheva01highlevel.html Petaflop supercomputers]
Developed by K.K Likharev and V. Semenov at SUNY Stony Brook
* [http://pavel.physics.sunysb.edu/RSFQ/Research/WhatIs/rsfqwte1.html An excellent introduction to the basics and links to further information] at the
State University of New York at Stony Brook.
* K.K. Likharev and V.K. Semenov, IEEE Trans. Appl. Supercond. 1 (1991), 3.
* A. H. Worsham, J. X. Przybysz, J. Kang, and D. L. Miller, "A single flux quantum cross-bar switch and demultiplexer," IEEE Trans. on Appl. Supercond., vol. 5, pp. 2996--2999, June 1995.
* [http://citeseer.ist.psu.edu/zinoviev96feasibility.html Feasibility Study of RSFQ-based Self-Routing Nonblocking Digital Switches (1996)]
* [http://citeseer.ist.psu.edu/zinoviev97design.html Design Issues in Ultra-Fast Ultra-Low-Power Superconductor Batcher-Banyan Switching Fabric Based on RSFQ Logic/Memory Family (1997)]
* [http://citeseer.ist.psu.edu/gaj95clock.html A Clock Distribution Scheme for Large RSFQ Circuits (1995)]
* [http://www.ece.rochester.edu/~sde/research/publications/etc98/FEDReport.pdf Josephson Junction Digital Circuits -- Challenges and Opportunities]
* [http://www.hypres.com Commercial RSFQ Fabrication]
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