2022.02.04
Professor Jae-Hoon Kim's research team from the Department of Physics at Yonsei University collaborated with the Institute for Basic Science (IBS) Kang-Sang-Relationship Research Center (Former Associate Director Park Je-Geun, Seoul National University Professor of Physics and Astronomy), Professor Hyeon-Sik Jeong (Department of Physics, Sogang University), and Professor Young-Woo Son (Department of Computational Science, Institute of Advanced Science and Technology), etc. Through the research conducted, a unique signal was discovered in a magnetic two-dimensional material, and it was revealed that this signal is a new exciton in a quantum polyhedral state in which one electron is divided into several atoms.
Exciton is a particle consisting of free electrons and holes(empty seats where electrons escape), because it is a quantum state that emits photons quantum light source(light source that emits light(photons)according to the quantum state)is considered to be an important key to the necessary quantum information communication.
The new exciton discovered this time is a form in which one electron is divided into several atoms, like Schrödinger's cat, where life and death are superimposed. This exciton is a new quantum phenomenon that has never been theoretically predicted. Here, "Schrödinger's Cat" refers to a thought experiment that combats the indeterminacy of quantum mechanics. When the cat in the box is said to have a 50% chance of dying because of the radioactive material next to it, the dead cat and the mountain cat are nested until the box is opened and observed.
The results of the study were first published in the global journal Nature(IF 42.778)online at 0: 00 p.m. on July 21. (Print edition will be published on July 30.)
The researchers found that coherence, wavelength multiple frequencies and waveforms match in a two-dimensional magnetic material(nickel trifluoride, hereinafter NiPS3). Lasers with a single wavelength are higher than natural light with a variety of wavelengths.) This very strong exciton signal was identified by three different experiments and this signal data was theoretically analyzed to determine that the exciton found this time is a quantum multi-body state.
Two-dimensional materials in planar form have unique physical properties with electronic interactions that do not appear in one or three dimensions. NiPS3 used in this experiment is one of the Van der Waals materials that have magnetism and are separated into thin two-dimensional layers(materials that can be separated into thin atomic layers because the layers are bound by weak electrical forces called van der Waals bonds).
The researchers found a strong light signal in two-dimensional NiPS3 through a light emission experiment that measures light absorbed by the material and then emitted again. Later, through light absorption experiments, it was confirmed that this signal reflects the unique electronic structure of the material rather than simply coming from impurities or structural defects, and resonance inelastic X-ray scattering experiments to measure the momentum and energy dispersion relationship of light were also performed, and then carried out a vast calculation with many-body theory, a quantum mechanical theory that fully considers the interaction
Quantum many-body magnetic excitons are fundamentally new quantum states, which are expected to contribute to the study of two-dimensional matter quantum phenomena and advance the quantum information technology revolution. Two-dimensional materials can be assembled in layers like graphene, so they have great applicability. In addition, the light generated in the exciton can be extended to a quantum information communication that transmits information to the quantum state, at this time it is important to better understand the quantum state that the exciton has. This exciton shows a very narrow energy width, high cohesion signal, and unusual physical phenomena such as superconductors and superfluids are also associated with cohesion. “Unusual quantum states are very rare in two-dimensional materials,”said Park Jeong-geun, former Deputy Research Director of the IBS Steel-related Materials Research Group."He said the meaning.
This study was the result of collaborative research by Park Je-geun, former Associate Research Director of the IBS Kang Sang-related Materials Research Group(Professor of Physics and Astronomy, Seoul National University), Professor of Physics, Yonsei University, Professor of Physics, Hyun-sik Chung, Professor of Physics, Sogang University, and Professor of Computational Science, Young-woo Son, who obtained his Ph. D. from the Yonsei Physics Department. On the other hand, the co-authors, Professor Jae-hoon Kim, Professor Young-woo Son, and Professor Hyun-sik Chung, are all researchers at the Van Der Waals Materials Research Center(Center Director Seong-il Im, Professor of Physics), Yonsei University.