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HP's 'Crossbar Latch' to Replace Transistors?

Researchers at HP have come up with a new signal technology they claim could replace transistors in computers one day.

In a paper published in Tuesday's Journal of Applied Physics, three members of HP Labs' Quantum Science Research (QSR) group demonstrated what they call a "crossbar latch."

A latch consists of a single wire acting as a signal line, crossed by two control lines with an electrically switchable nanoscale junction where they intersect. The technology is so small, HP claims thousands of the strands could fit across the diameter of a human hair.

"We are re-inventing the computer at the molecular scale," Stan Williams, HP senior fellow, QSR director and one of the authors of the paper, said in a statement. "The crossbar latch provides a key element needed for building a computer using nanometer-sized devices that are relatively inexpensive and easy to build."

Similar to the way that silicon-based transistors perform in computers today, the researchers said the crossbar latches use a sequence of voltage impulses to the control lines and using switches arranged in opposite polarities.

The result is that the crossbar latches can perform the three basic operations that comprise the primary logic of a circuit and are essential for basic computer functions. In addition, the researchers said the new latch technology could also restore a circuit to its ideal voltage. That would let designers chain many simple gates together, allowing them to perform computations.

Researchers are not ready to discard the current transistor technology just yet. While current silicon transistor technology can also perform the same operations and restore signals, the researchers generally believe 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," Phil Kuekes, senior computer architect with HP's QSR and another one of the paper's authors, said in a statement. "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. Duncan Stewart, a QSR scientist and the third author, performed most of the testing that demonstrated that the device actually works.

"We have previously demonstrated that we could make a working memory with molecular-scale junctions and logic devices that could perform simple logic operations," 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."

HP said its researchers are also looking at how to use the latches in tiny devices so manufacturers can produce them cheaper and in mass quantities.

The research on the crossbar latch was partially supported by the Defense Advanced Research Projects Agency.