Newswise — Scientists have made a major step toward using quasiparticles — particles displaying collective behavior — to hunt for axions. Their findings open new paths for harnessing quasiparticles to search for dark matter and to develop new quantum technologies.
No one has ever seen axions. But scientists have theorized their existence as a way to explain some of the biggest questions in particle physics and the nature of dark matter, the mysterious substance that constitutes most of the mass of the cosmos. Confirming the existence of axions could lead to insights into the history and composition of the universe itself.
“The axion has been one of the most sought-after fundamental particles, on par with the Higgs boson, ever since it was proposed in the 1970s,” said Ivar Martin, senior physicist at the U.S. Department of Energy’s (DOE) Argonne National Laboratory. “Experimentalists have tried to create and measure them in the lab in the ingenious ‘light shining through the wall’ experiments or tried to detect the existing dark-matter axions that are expected to permeate our galaxy in the Axion Dark Matter Experiment by converting them into photons.”
Now in a groundbreaking experiment, an international team led by Harvard University and King’s College London has made a significant step toward using quasiparticles to hunt for axions. Quasiparticles are particles that display collective behavior, which means they act together as if they were a single unit.
“This new experiment succeeded in exciting and detecting a material realization of axions, which has the same unique traits as the fundamental axion, but microscopically corresponds to a special magnetic excitation.” — Ivar Martin, Argonne senior physicist
The researchers’ findings open new paths for harnessing quasiparticles to search for dark matter and to develop new quantum technologies. Martin and Michael Smith, also an Argonne researcher, were co-authors on the study, which was published in Nature.
“Axion quasiparticles are simulations of axion particles, which can be further used as a detector of actual particles,” said senior author Suyang Xu, assistant professor of chemistry at Harvard. “If a dark matter axion hits our material, it excites the quasiparticle, and, by detecting this reaction, we can confirm the presence of the dark matter axion.”
“This new experiment succeeded in exciting and detecting a material realization of axions, which has the same unique traits as the fundamental axion, but microscopically corresponds to a special magnetic excitation,” added Martin.
The researchers used manganese bismuth telluride, a material renowned for its particular electronic and magnetic properties. By crafting this material into a two-dimensional crystal structure, they established a platform ideal for nurturing axion quasiparticles. This process involved precision nanofabrication engineering, in which the material was meticulously layered to enhance its quantum characteristics.
“It is both a very rich material platform and also it is very difficult to work with,” said lead author Jian-Xiang Qiu, a Harvard graduate student. “Because it’s air-sensitive, we needed to exfoliate down to a few atomic layers to be able to tune its property properly.”
Operating in a highly controlled environment, the team coaxed the axion quasiparticles into revealing their dynamic nature in manganese bismuth telluride. To accomplish this delicate feat, the team used a series of sophisticated techniques including ultrafast laser optics. Innovative measurement tools allowed them to capture movements of axion quasiparticles with precision, turning an abstract theory into a clearly visible phenomenon.
Argonne’s researchers contributed a detailed theoretical understanding of the magnetic excitation underlying the material realization of axions.
By demonstrating the coherent behavior and intricate dynamics of axion quasiparticles, the researchers not only affirmed long-held theoretical ideas in the field of condensed matter physics but also have laid the groundwork for future technological developments. Martin and collaborators are currently exploring nonlinear optical phenomena that can be enabled by the unusual axion-light coupling.
In the field of particle physics and cosmology, this new observation of the axion quasiparticle can be used as a dark matter detector, which the researchers have described as a “cosmic car radio” that may be poised to become the most accurate dark matter detector yet.
Dark matter remains one of the most profound mysteries in physics, constituting about 85% of the universe’s mass without detection. By tuning into specific radio frequencies emitted by axion particles, the team aims to capture dark matter signals that have eluded previous technology. The researchers believe it could help discover dark matter within 15 years.
“This is a really exciting time to be a dark matter researcher. There are as many papers being published now about axions as there were about the Higgs boson a year before it was found,” said co-author David Marsh, a lecturer at King’s College London. “Experiments proposed that axions emitted a frequency in 1983, and we now know we can tune in to it — we’re closing in on the axion and fast.”
Xu is confident that the team’s multifaceted approach enabled their pioneering success.
“Our work is made possible by a highly interdisciplinary approach involving condensed matter physics, material chemistry, as well as high-energy physics,” Xu said. “It showcased the potential of quantum materials in the realm of particle physics and cosmology.”
Moving forward, the researchers plan to deepen their exploration of axion quasiparticles’ properties all while refining experimental conditions for greater precision.
“The goal for the future is obviously to have an experiment that probes axion dark matter, which would definitely be super beneficial for the whole particle physics community that is interested in axions,” said co-author Jan Schütte-Engel, a physicist at the University of California, Berkeley.
This research was supported by the Center for the Advancement of Topological Semimetals, an Energy Frontier Research Center funded by the DOE Office of Science (DOE-SC); the DOE-SC’s Office of Basic Energy Sciences; the Air Force Office of Scientific Research; the U.S. National Science Foundation; the Sloan Foundation; the Corning Fund for Faculty Development; the Japan Science and Technology Agency; the Japan Society for the Promotion of Science; the German Research Foundation; Academia Sinica in Taiwan; the National Cheng Kung University in Taiwan; the National Center for Theoretical Sciences in Taiwan; the Government of India; and UK Research and Innovation.
Argonne National Laboratory seeks solutions to pressing national problems in science and technology by conducting leading-edge basic and applied research in virtually every scientific discipline. Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science.
The U.S. Department of Energy’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, visit https://energy.gov/science.
