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Electrons at the Speed Limit


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A short laser pulse travels through a diamond (black spheres) and excites electrons inside it.

Researchers at the Swiss Federal Institute of Technology in Zurich have explored the ultimate speed of electrons when controlled by electric fields.

Credit: Matteo Lucchini/ETH Zurich

Researchers at the Swiss Federal Institute of Technology in Zurich (ETH Zurich) led by professor Ursula Keller have explored the ultimate speed of electrons when controlled by electric fields, which has implications for future petahertz electronics.

Keller and colleagues' exposure of a 50-nanometer-thick diamond fragment to an infrared laser pulse lasting a few femtoseconds demonstrated that the laser light's electric field oscillated back and forth five times and excited the electrons. The researchers saw the absorption varied characteristically following the rhythm of the oscillating electric field of the infrared pulse.

A joint ETH/Tsukuba University of Japan project was conducted to model the reaction of the electrons to the laser pulse on a supercomputer, which determined the absorption was consistent with the Zurich measurements.

"The advantage of the simulations compared to the experiment...is that several of the effects that occur in real diamond can be switched on or off, so that eventually we were able to ascribe the characteristic absorption behavior of diamond to just two such energy bands," says ETH postdoctoral researcher Matteo Lucchini.

The results offered proof the dynamical Franz-Keldysh effect was responsible for the absorption in diamond under the influence of the laser pulse.

From ETH Zurich
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Abstracts Copyright © 2016 Information Inc., Bethesda, Maryland, USA


 

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