NIST's superconducting synapse may be missing piece for 'artificial brains'

NIST's superconducting synapse may be missing piece for 'artificial brains'
Illustrations showing the basic operation of NIST's artificial synapse, which couldconnect processors and store memories in future neuromorphic computers operatinglike the human brain. A synapse is a connection or switch between two brain cells.NIST's artificial synapse is a tiny metal cylinder that processes incoming electricalspikes to customize spiking output signals based on a tunable internal design.Researchers apply current pulses to control the number of nanoclusters pointing inthe same direction, as depicted in the "disordered" versus "ordered" cartoons. Thisdesign, in which different inputs alter the alignment and resulting output signals, isinspired by how the brain operates. Credit: NIST



A synapse is a connection or switch between two brain cells. NIST's artificial synapse—a squat metallic cylinder 10 micrometers in diameter—is like the real thing because it can process incoming electrical spikes to customize spiking output signals. This processing is based on a flexible internal design that can be tuned by experience or its environment. The more firing between cells or processors, the stronger the connection. Both the real and artificial can thus maintain old circuits and create new ones. Even better than the real thing, the NIST synapse can fire much faster than the human brain—1 billion times per second, compared to a brain cell's 50 times per second—using just a whiff of , about one ten-thousandth as much as a human synapse. In technical terms, the spiking energy is less than 1 attojoule, lower than the background energy at room temperature and on a par with the chemical energy bonding two atoms in a molecule.

"The NIST synapse has lower energy needs than the human synapse, and we don't know of any other artificial synapse that uses less energy," NIST physicist Mike Schneider said.



The NIST synapse is a Josephson junction, long used in NIST voltage standards. These junctions are a sandwich of superconducting materials with an insulator as a filling. When an electrical current through the junction exceeds a level called the , voltage spikes are produced. The synapse uses standard niobium electrodes but has a unique filling made of nanoscale clusters of manganese in a silicon matrix.

Animation of how NIST's artificial synapse works. Credit: Sean Kelley/NIST

The nanoclusters—about 20,000 per square micrometer—act like tiny bar magnets with "spins" that can be oriented either randomly or in a coordinated manner.

"These are customized Josephson junctions," Schneider said. "We can control the number of nanoclusters pointing in the same direction, which affects the superconducting properties of the junction."






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More information: M.L. Schneider, C.A. Donnelly, S.E. Russek, B. Baek, M.R. Pufall, P.F. Hopkins, P.D. Dresselhaus, S. P. Benz and W.H. Rippard. Ultra-low power artificial synapses using nano-textured magnetic Josephson junctions. Science Advances. Published on January 26, 2018 advances.sciencemag.org/content/4/1/e1701329
Journal information: Science Advances

Citation: NIST's superconducting synapse may be missing piece for 'artificial brains' (2018, January 26) retrieved 28 July 2021 from https://phys.org/news/2018-01-nist-superconducting-synapse-piece-artificial.html

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