Scientists determine absolute speed limit for electronics

Scientists determine absolute speed limit for electronics
Researchers at TU Wien have determined the ‘speed limit’ for electronics through quantum mechanics.

While computer chips continue to work with ever shorter signals and time intervals, a limit to the speed of electronic devices could reach a physical limit, with researchers discovering limit to the speed of signal generation and signal transmission. 

TU Wien, TU Graz and the Max Planck Institute of Quantum Optics in Garching have been able to explore the limits, confirming that the speed of electronics can not be increased beyond one petahertz (one million gigahertz), even if the material is excited in an optimal way with laser pulses. Though this number is incredibly large, the researchers believe that the realistic technical upper limits of this technology are likely to be considerably lower that one petahertz. 

In microchips, electricity is controlled with the help of electromagnetic fields, with a transistor allowing electrical current to flow be blocked, converting an electromagnetic field into an electrical signal. 

The researchers tested the limits of this conversion of electromagnetic fields to current, using laser pules rather than transistors as laser pules are the fastest, most precise electromagnetic fields available. 

Prof. Joachim Burgdörfer, Institute for Theoretical Physics, TU Wien, commented: This laser pulse shifts the electrons into a higher energy level, so that they can suddenly move freely. That way, the laser pulse turns the material into an electrical conductor for a short period of time. As soon as there are freely moving charge carriers in the material, they can be moved in a certain direction by a second, slightly longer laser pulse. This creates an electric current that can then be detected with electrodes on both sides of the material.

"For a long time, such processes were considered instantaneous. "It turns out that about one petahertz is an upper limit for controlled optoelectronic processes.”

Photo credit: Yurchanka Siarhei, Shutterstock

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