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Illustration of how electrons move between two nanoantenna arms. (University of Konstanz)

Physicists Just Achieved Conduction of Electricity at Close to The Speed of Light

DAVID NIELD
27 DEC 2019

When it comes to data transfer and computing, the faster we can shift electrons and conduct electricity the better – and scientists have just been able to transport electrons at sub-femtosecond speeds (less than one quadrillionth of a second) in an experimental setup.

 

The trick is manipulating the electrons with light waves that are specially crafted and produced by an ultrafast laser. It might be a long while before this sort of setup makes it into your laptop, but the fact they pulled it off promises a significant step forward in terms of what we can expect from our devices.

Right now, the fastest electronic components can be switched on or off in picoseconds (trillionths of a second), around 1,000 times slower than a femtosecond.

With their new method, the physicists were able to switch electric currents at around 600 attoseconds (one femtosecond is 1,000 attoseconds).

"This may well be the distant future of electronics," says physicist Alfred Leitenstorfer from the University of Konstanz in Germany. "Our experiments with single-cycle light pulses have taken us well into the attosecond range of electron transport."

Leitenstorfer and his colleagues were able to build a precise setup at the Centre for Applied Photonics in Konstanz. Their machinery included both the ability to carefully manipulate ultrashort light pulses, and to construct the necessary nanostructures.

The laser used by the team was able to push out one hundred million single-cycle light pulses every single second in order to generate a measurable current. Using nanoscale gold antennae in a bowtie shape (see the image above), the electric field of the pulse was concentrated down into a gap measuring just six nanometres wide (six thousand-millionths of a metre).

 

As a result of their specialist setup and the electron tunnelling and accelerating it produced, the researchers could switch electric currents at well under a femtosecond – less than half an oscillation period of the electric field of the light pulses.

Getting beyond the restrictions of conventional silicon semiconductor technology has proved a challenge for scientists, but using the insanely fast oscillations of light to help electrons pick up speed could provide new avenues for pushing the limits on electronics.

And that's something that could be very advantageous in the next generation of computers: scientists are currently experimenting with the way that light and electronics could work together in all sorts of different ways.

Eventually, Leitenstorfer and his team think that the limitations of today's computing systems could be overcome using plasmonic nanoparticles and optoelectronic devices, using the characteristics of light pulses to manipulate electrons at super-small scales.

"This is very basic research we are talking about here and may take decades to implement," says Leitenstorfer.

The next step is to experiment with a variety of different setups using the same principle. This approach might even offer insights into quantum computing, the researchers say, although there's a lot more work to get through yet - we can't wait to see what they'll achieve next.

The research has been published in Nature Physics.