Molecular Scale Computing Breakthrough
Staff -- Semiconductor International, 3/1/2005
Hewlett-Packard researchers said they have proven that a technology they invented could replace the transistor. In a paper published in the Journal of Applied Physics, three members of HP Labs' Quantum Science Research (QSR) group proposed and demonstrated 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 reinventing 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."
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 computations.
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 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."
