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The "Hidden" Pair Is Called Metamaterial Design Opens up New Ways

wallpapers Tech 2020-08-20

Research Findings on Duality

When you tap a watermelon to see if it is ripe, the principle used is to detect the structure of the substance inside with sound waves. Physicists at the University of Chicago used the same concept to explore how sound waves pass through patterned structures and discovered a strange phenomenon: completely different structures sound the same. Vincenzo Vitelli, professor of physics at the James Frank Institute, said: What excites us is that it cannot be explained by existing concepts, such as spatial symmetry.
In fact, what the research team discovered is a duality, a kind of "hidden" symmetry that connects apparently unrelated systems. This discovery may one day help design metamaterials and even miniature devices that process acoustically encoded information. Over the years, physics has established a framework that can predict the properties of objects based on their spatial symmetry.

The Spin Properties of Duality in Electrons

This can tell you a lot about how molecules vibrate. What if these dualities could be used to give a material properties that it would otherwise not possess? In the past few years, there has been great interest in a field called metamaterials.
Researchers envision using this method to capture a particle, such as a phonon, and give it properties that it usually doesn't possess. Electrons have a property called "spin", which is used as the basis for some of the latest high-tech electronic products. Phonons have no spin, but if scientists can shape the structure of materials and give phonons a "false spin", it is possible to use them in phononic devices, but they have different capabilities. For example, thermal control. By moving phonons, people can process the information stored in their pseudo-spins. Researchers call this concept "mechanical spintronics."

Future Breakthrough of Duality

Research has shown how duality enhances the symmetry of the dynamic matrix (or Hamiltonian), so that metamaterial designs with emergent properties can escape the analysis of standard group theory. As an illustration, the researchers considered twisted Kagome lattices, which are reconfigurable mechanical structures that change shape through a collapse mechanism. The study observed a pair of different configurations along the structure, showing the same vibration spectrum and relative elastic modulus.
The critical point corresponds to a self-dual structure with isotropic elasticity, even when there is no spatial symmetry and double degenerate spectrum in the entire Brillouin zone. The degenerate spectrum originated from a version of Kramers theorem, in which the invariance of fermions time reversal is replaced by hidden symmetry that appears at the self-dual point. The normal mode of the self-dual system exhibits a non-Abelian geometric phase that affects the semi-classical propagation of the wave packet, resulting in a non-commutable mechanical response. The research results provide hope for complete calculations and mechanical spintronics, because it can manipulate the synthetic spins carried by phonons in real time.

Tag: spin   metamaterials   Duality