Researchers at Graz University of Technology (TU Graz) have discovered a promising technique for generating magnetic fields using light.
Their findings, published in the Journal of the American Chemical Society, involve stimulating specific molecules with infrared light pulses to create tiny magnetic fields.
This approach, if proven successful in upcoming experiments, could hold significant potential for building quantum computer circuits.
The idea builds upon the well-known principle that molecules vibrate when they absorb light.
Dr. Andreas Hauser, from TU Graz's Institute of Experimental Physics, wondered if these vibrations could be harnessed to produce magnetic fields. Since moving charged particles (like the positively charged protons in atomic nuclei) generate magnetic fields, this theory held promise.
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| Andreas Hauser from the Institute of Experimental Physics at TU Graz. Credit: Lunghammer – TU Graz |
The team used metal phthalocyanines, flat, ring-shaped molecules, as a test case.
Their calculations, leveraging both established principles from early laser spectroscopy and modern supercomputer simulations, revealed that these molecules indeed produce small, nanometer-sized magnetic fields when excited by infrared pulses. The specific type of light used – circularly polarized light with a twisting motion – plays a crucial role.
Imagine a couple dancing the rumba: their combined steps forward and backward, along with side-to-side movements, create a small, circular path.
Similarly, explains Dr. Hauser, the circular motion of excited atomic nuclei in the phthalocyanines generates a tiny, localized magnetic field.
The exciting part? By carefully manipulating the infrared light, researchers can control the strength and direction of this magnetic field. This essentially transforms the molecules into light-controlled magnetic switches, potentially paving the way for building quantum computer circuits.
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| Schematic representation of a metal phthalocyanine molecule that is set into two vibrations (red and blue), creating a rotating electric dipole moment (green) in the molecular plane and thus a magnetic field. |
The next step for Dr. Hauser and his team is experimental verification. They will collaborate with colleagues from TU Graz's Institute of Solid State Physics and the University of Graz to generate these magnetic fields in a controlled setting.
However, a challenge arises: placing the molecules on a surface, a necessary step for practical applications, alters the physical environment, potentially affecting how light excites the molecules and the resulting magnetic field. "We need to find a supporting material with minimal impact on this mechanism," explains Dr. Hauser.
Through further calculations simulating the interaction between the molecules, the supporting surface, and the light, the researchers aim to identify the most promising configurations before moving on to experimental validation.
Sources:
Published 14 May 2024, Journal of the American Chemical Society; Molecular Pseudorotation in Phthalocyanines as a Tool for Magnetic Field Control at the Nanoscale.
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