“Memristors” are four decades in the making, but it turns out that this fourth kind of circuit element (beyond the inductor, capacitor, and resistor) might have more potential to change computing than even its creators first believed.
In a study this week in Nature, researchers with Hewlett-Packard report that they’ve achieved “stateful logic” with their memristor, whose name derives from a mashup of “memory” and “resistor.” In a nutshell, stateful logic means that the ‘state’ of the memristor acts as both the computer and the memory. That’s a pretty big change from current computers, which typically load data from memory, perform operations on it, and then send it back [Nature]. In addition, memristors can store information even in the absence of electrical current.
While an engineer named Leon O. Chua theorized memristors back in 1971, they remained strictly theoretical until HP researchers created the first one two years ago. But while the researchers previously thought of it as just another kind of memory, this study’s find—that they themselves can perform logic—suggests memristors could go much further than that. Such a discovery can pave the way for chips that can both perform calculations and hold data, potentially eliminating the need for a traditional core CPU [CNET].
The H.P. technology is based on the ability to use an electrical current to move atoms within an ultrathin film of titanium dioxide. After the location of an atom has been shifted, even by as little as a nanometer, the result can be read as a change in the resistance of the material. That change persists even after the current is switched off, making it possible to build an extremely low-power device [The New York Times]. And the device’s speed is equally impressive: Stan Williams of HP, one of the lead authors, says they can turn on and off in a nanosecond.
Memristor development currently isn’t close to competing with ordinary silicon, but the ever-confident Williams and this team argue that they could overtake flash memory within three years, and someday surpass the phase-change memory of their competitors. For Chua, the dream goes further. “Our brains are made of memristors,” he said, referring to the function of biological synapses. “We have the right stuff now to build real brains” [The New York Times].
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Image: Stan Williams / Nature