Optoelectric logic gate operates at a frequency of one million gigahertz

In their work, researchers from the Universities of Rochester and Friedrich-Alexander in Erlangen-Nuremberg

used synchronized laser pulses that generate a burst of real and virtual charge carriers in graphene.

In the experiment of scientists, the input signals of the logicalgates represent the shape or phase of two synchronized laser pulses, each of which is selected only to generate a burst of real or virtual charge carriers. Depending on the laser phases used, these two current contributions can either add up or cancel out. A pure electrical signal can be assigned logic information of 0 or 1, resulting in an ultra-fast logic element.

What is amazing about this logic gate is thatit's that the operations are not done in gigahertz as in conventional computers, but in petahertz, which is a million times faster. This is due to the fact that very short laser pulses are used, which occur in one millionth of a billionth of a second.

Ignacio Franco, study co-author at the University of Rochester

Researchers explain that laser pulsescan produce electricity much faster than any traditional method, and do so without applied voltage. For example, when illuminating tiny graphene-based wires connecting two gold metals, an ultrashort laser pulse drives or “excites” electrons and directs them in a certain direction, thus generating a pure electrical current.

Scientists have found that in the compoundsgold-graphene-gold can generate two kinds of charged particles: "real" and "virtual". The authors of the work refer to the first type of electrons that remain in directed motion even after the laser pulse is turned off, and to the second type, those that move only during illumination.

Researchers have learned to control the generated flows of real and virtual particles by changing the shape of the laser pulse. It was this technology that made it possible to create a logic module.

"Probably it will be a very long time beforethan this technique can be used in a computer chip, but at least now we know that light wave electronics is practically possible, ”says Tobias Bulaki, co-author of the study from the Friedrich-Alexander University.

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