HP Labs finds fourth fundamental circuit element

HP Labs finds fourth fundamental circuit element

Researchers from HP Labs say that they have proven the existence of the previously only theorized fourth fundamental circuit element in electrical engineering. The Information and Quantum Systems Lab, led by R. Stanley Williams, presented the mathematical model and a physical example of a “memristor” — a blend of “memory resistor” — which has the unique property of retaining a history of the information it has acquired.

Leon Chua of the UC Berkeley initially theorized about and named the element in an academic paper published 37 years ago. Chua argued that the memristor was the fourth fundamental circuit element, along with the resistor, capacitor, and inductor, and that it had properties that could not be duplicated by any combination of the other three elements.

Williams and his colleagues created a memristor while experimenting with very tiny circuits. They sandwiched a nanoscopic film of a semiconductor (titanium dioxide) between two slivers of metal (platinum). It’s only at the nanoscale that the behavior of memristors begins to be detectable.

The resistance of the memristor changes depending on the amount of voltage and the time for which that voltage has been applied to the device. This means that a computer created from memristive circuits can “remember” what has happened to it previously, and freeze that memory when the circuit is turned off. This quality could allow computers to turn off and on again in an instant, as all the components could revert to their last state instantly, rather than having to “boot up.”

A mathematical model and a physical example that prove the memristor’s existence appear in a paper published in the April 30 issue of the journal Nature . For more information, visit http://www.hpl.hp.com/news/2008/apr-jun/memristor.html.

Jim Harrison