Who Needs Transistors? HP Scientists Create New Computing Breakthrough at Molecular Scale - (DARPA)
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Who Needs Transistors? HP Scientists Create New Computing Breakthrough at
February 01, 2005
Research could send transistors the way of the vacuum tube
HP today announced its researchers have proven that a technology they
invented could replace the transistor - the fundamental building block of
computers for the last half century - leading to a new way to construct
computers in the future.
In a paper published in today's Journal of Applied Physics, three
members of HP Labs' Quantum Science Research (QSR) group propose and
demonstrate a "crossbar latch," which provides the signal restoration and
inversion required for general computing without the need for transistors.
The technology could result in computers that are thousands of times more
powerful than those that exist today.
"We are re-inventing the computer at the molecular scale," said Stan
Williams, HP Senior Fellow and QSR director, and one of the authors of the
paper. "The crossbar latch provides a key element needed for building a
computer using nanometer-sized devices that are relatively inexpensive and
easy to build."
QSR works on nanoscale electronic devices that will first supplement, and
someday perhaps replace, silicon technology, which is expected to reach its
physical limits in about a decade. In addition to exploring the fundamental
scientific principles of computing at the molecular level, QSR is also
looking at architectural issues and determining how such tiny devices -
thousands of which could fit across the diameter of a human hair - could be
fabricated economically and in mass quantities.
The experimentally demonstrated latch consists of a single wire acting as a
signal line, crossed by two control lines with an electrically switchable
molecular-scale junction where they intersect. By applying a sequence of
voltage impulses to the control lines and using switches oriented in
opposite polarities, the latch can perform the NOT operation, which, along
with AND and OR, is one of three basic operations that make up the primary
logic of a circuit and are essential for general computing. In addition, it
can restore a logic level in a circuit to its ideal voltage value, which
allows a designer to chain many simple gates together to perform
Standard semiconductor circuits require three-terminal transistors to
perform the NOT operation and restore signals. However, it is generally
believed that transistors will not be able to shrink down to the size of a
few nanometers and remain operable.
"Transistors will continue to be used for years to come with conventional
silicon circuits," said Phil Kuekes, senior computer architect, QSR, another
one of the paper's authors, "but this could someday replace transistors in
computers, just as transistors replaced vacuum tubes and vacuum tubes
replaced electromagnetic relays before them."
Kuekes was previously awarded a patent on the crossbar latch (U.S.
6,586,965) in July 2003, and the Journal of Applied Physics report, titled
"The crossbar latch: Logic value storage, restoration and inversion in
crossbar circuits," demonstrates the application of the technology. Duncan
R. Stewart, a QSR scientist and the third author, performed most of the
testing that demonstrated that the device actually works. The paper
underwent rigorous peer review before being published.
"We have previously demonstrated that we could make a working memory with
molecular-scale junctions and logic devices that could perform simple logic
operations such as AND and OR," Stewart said. "With the crossbar latch, we
now have the final component theoretically needed for performing the
multiple processing steps required for useful computing at the nanoscale."
The research on the crossbar latch was partially supported by the Defense
Advanced Research Projects Agency (DARPA).