Researchers from FAU, the University of Rostock, and the University of Konstanz have precisely controlled electron emission from metals by superimposing two laser fields of different strengths and frequencies. This groundbreaking discovery could lead to new quantum mechanical insights and enable electronic circuits that are a million times faster than current technology.
Physicists measure and control electron release from metals in the attosecond range.
By superimposing two laser fields of different strengths and frequency, the electron emission of metals can be measured and controlled precisely to a few attoseconds. Physicists from Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), the University of Rostock and the University of Konstanz have shown that this is the case. The findings could lead to new quantum-mechanical insights and enable electronic circuits that are a million times faster than today.
Light is capable of releasing electrons from metal surfaces. This observation was already made in the first half of the 19th century by Alexandre Edmond Becquerel and later confirmed in various experiments, among others by Heinrich Hertz and Wilhelm Hallwachs. Since the photoelectric effect could not be reconciled with the light wave theory, Albert Einstein came to the conclusion that light must consist not only of waves, but also of particles. He laid the foundation for quantum mechanics.
Strong laser light allows electrons to tunnel
With the development of laser technology, research into the photoelectric effect has gained a new impetus. “Today, we can produce extremely strong and ultrashort laser pulses in a wide variety of spectral colors,” explains Prof. Dr. Peter Hommelhoff, Chair for Laser Physics at the Department of Physics at FAU. “This inspired us to capture and control the duration and intensity of the electron release of metals with greater
Circuits a million times faster
In the experiment, the researchers were able to determine the duration of the electron flow to 30 attoseconds – thirty billionths of a billionth of a second. This ultra-precise limitation of the emission time window could advance basic and application-related research in equal measure. “The phase shift of the two laser pulses allows us to gain deeper insights into the tunnel process and the subsequent movement of the electron in the laser field,” says Philip Dienstbier. “This enables new quantum mechanical insights into both the emission from the solid state body and the light fields used.”
The most important field of application is light-field-driven electronics: With the proposed two-color method, the laser light can be modulated in such a way that an exactly defined sequence of electron pulses and thus of electrical signals could be generated. Dienstbier: “In the foreseeable future, it will be possible to integrate the components of our test setup – light sources, metal tip, electron detector – into a microchip.“ Complex circuits with bandwidths up to the petahertz range are then conceivable – that would be almost a million times faster than current electronics.
Reference: “Tunneling electrons” by Philip Dienstbier, Lennart Seiffert, Timo Paschen, Andreas Liehl, Alfred Leitenstorfer, Thomas Fennel and Peter Hommelhoff, 26 April 2023, Nature.
DOI: 10.1038/s41586-023-05839-6