Physicists are discovering an infinitesimally small world composed of a strange and surprising array of links, knots and winding. Some quantum materials have magnetic whirls called skyrmions that are described as subatomic hurricanes.
In an article published in Nature, a team of physicists discovered that electrons in quantum matter can link to one another in strange ways. In a new way, the work raises unexpected questions about the quantum properties of electronic systems by bringing together ideas in three areas of science.
Topology studies geometric properties that can be changed but not altered. The public became aware of topological quantum states in 2016 when Duncan Haldane, who is the Thomas D. Jones Professor of Mathematical Physics and Sherman Fairchild University Professor of Physics, was awarded the Nobel Prize.
Since that time, researchers have sought to expand this area of research to create a deeper understanding of quantum mechanics, such as in the field of quantum topology, which seeks to explain an electron's state as described by a property called its wave function. The senior author of the study said that this was the catalyst that led to the current research.
Hasan said that they are studying the shape of the wave functions of electrons.
The Weyl loop is a quantum mechanical structure that involves the winding of massless electron wave functions in a crystal. The massless Weyl loops were discovered in a compound composed of cobalt, manganese and gallium, with a chemical formula Co 2 MnGa. Many of the authors of the new study were included in this research. They understood that the Weyl loops produced exotic behaviors under applied electric and magnetic fields. The behaviors continued up to room temperature.
The Weyl loop is an example of a quantum mechanical wave function winding. The discoveries were reported in Nature in both 2020 and 2019.
The case of Co 2 MnGa turned out to be different from wave function winding considered in conventional theories.
The materials were grown by Professor Felser and her team at the Max Planck Institute for Chemical Physics of Solids in Germany.
When multiple Weyl loops co-exist, it becomes natural to ask whether they can link up and knot in certain ways.
The realization by Hasan's team sparked fundamental questions about linked Weyl loops and brought together a team of experts from around the world.
The international team collaborated for more than five years to expand on their earlier works. The team performed advanced photoemission spectroscopy experiments at some of the most cutting-edge radiation facilities in the world.
It turned out to be a fascinating puzzle that kept us hooked for a while, according to the lead author of the study.
The object was folded in on itself and wrapped around a higher-dimensional torus. Chang, who was a former researcher working with Hasan at Princeton, led one of the early theoretical studies of link topology in Physical Review Letters.
The research team found that the existing quantum theory of materials couldn't explain the structure. They recognized that knot theory might hold some clues.
The first example of where knot theory has been applied to understand the behavior of topological materials was found by Hasan. This is very exciting.
Some of the most important scientific discoveries arose when humans noticed new connections between mathematics and natural phenomena. Hasan said it was exciting to find unexpected examples of subtle mathematics in the experiments.
The researchers are going to expand their research. Although Hasan and his team focused on the behavior of magnets, they believe that knot theory can be used to explain other quantum behaviors.
Hasan emphasized that the researchers were involved in fundamental research and that their insights might help in the development of quantum computing.
More information: Ilya Belopolski et al, Observation of a linked-loop quantum state in a topological magnet, Nature (2022). DOI: 10.1038/s41586-022-04512-8The drumhead surface states and Weyl fermion lines were discovered in a room temperature magnet. The science.aav2327 is published in the journal Science.
Daniel S.nchez and his co-authors wrote about helicoid-arc quantum states. There is a DOI of 10.1038/s41586-019-1037-2.
Nature (2020) has a paper by Jia-Xin Yin et al. There is a DOI of 10.1038/s41586-020-2482-7.
Topological Hopf and Chain Link Semimetal States and Their Application to Co2MnGa was published in Physical Review Letters. There is a book titled "PhysRevLett."
Journal information: Physical Review Letters , Science , Nature Citation: Electrons in a crystal found to exhibit linked and knotted quantum twists (2022, May 20) retrieved 20 May 2022 from https://phys.org/news/2022-05-electrons-crystal-linked-quantum.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
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