Wednesday, February 02, 2005
HP Re-invents the Transistor
Here's where we separate the Geeks from the Nerds: 
In a paper published in Tuesday's Journal of Applied Physics, HP said three members of its Quantum Science Research group propose and demonstrate a "crossbar latch," which provides the signal restoration and inversion required for general computing without the need for transistors.
HP said in a statement that the technology could result in computers that are thousands of times more powerful than those that exist today. "We are reinventing the computer at the molecular scale," said Stan Williams, one of the authors of the paper, 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."
Okay, don't go running into the halls, screaming. A "crossbar 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. (With me, so far?) 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 computations.
What makes that important? Standard semiconductor circuits require three-terminal transistors to perform the NOT operation and restore signals. And guess what? the standard stuff isn't going to be able to shrink down small enough to work. (The junction in a crossbar latch is about 1/30th the size of the one in a standard transisitor.)
Don't start chucking out your transistor radios and such. This was just a test, only a test. Had it been an actual demonstration of existing working technology we'd all be in deep do-do. As is, it'll be a few years (somewhere around 2019 or so) before it even begins to replace what we have now.
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