Discovery of Quantum Multibody Excitons... A New Era in Quantum Information Communication

[Asia Economy Reporter Junho Hwang] A magnetic exciton, in which a single electron exists divided among multiple atoms, has been discovered by a domestic research team. Magnetic excitons are rare to find, and it has been revealed that this exciton exhibits a new quantum phenomenon. The light generated from this exciton can be utilized in quantum information communication that transmits information in quantum states, and it is expected to become a new foundational technology for the commercialization of quantum information technology.

The Institute for Basic Science announced on the 20th that Professor Jeon Jae-geun of the Department of Physics and Astronomy at Seoul National University (former deputy director of the Strongly Correlated Matter Research Group), together with Professor Jung Hyun-sik of Sogang University, Professor Kim Jae-hoon of Yonsei University, and Professor Son Young-woo of the Institute for Advanced Study, discovered a new exciton in a magnetic two-dimensional material where a single electron exists divided among multiple atoms in a quantum many-body state. The research results were introduced on the 21st (local time) in the international journal Nature.

A Single Electron Existing Across Multiple Atoms

This is the crystal structure of bulk trisulfide nickel phosphide (NiPS3). Each layer of the two-dimensional magnetic van der Waals material used in the experiment is composed of a hexagonal structure. The van der Waals bonds between layers are weak, allowing the layers to be easily separated. Although the spin directions are fixed as in ferromagnetism, the adjacent spins are oriented in opposite directions, resulting in an antiferromagnetic material that does not exhibit overall magnetism.

The research team discovered a very strong exciton signal in magnetic nickel trisulfide (NiPS3) and identified that this exciton is in a quantum many-body state.

NiPS3 is one of the van der Waals materials that exhibit magnetism and can be separated into thin two-dimensional layers. Van der Waals materials are substances where layers are held together by weak electrical forces, allowing them to be separated into thin atomic layers.

The team conducted photoluminescence experiments on NiPS3, measuring the light absorbed by the material and then re-emitted, capturing a very strong exciton signal with coherence. Coherence refers to the matching of multiple wavelengths and waveforms. Lasers, which have a single wavelength, have higher coherence compared to natural light with various wavelengths.

Furthermore, the researchers proved that the captured exciton is in a quantum many-body state through resonant inelastic X-ray scattering experiments that measure the momentum and energy dispersion of light. Through many-body calculations handling approximately 1.5 million cases, they revealed that this exciton is theoretically caused by the known Zhang-Rice quantum many-body state.

Potential Application in Quantum Information Communication

This is the exciton signal obtained through photoluminescence and photoabsorption experiments on NiPS3. In graph (a), you can see the results of measuring light emitted from a two-dimensional magnetic material. Light with a specific energy appears strongly, which is evidence of excitons. The coherence is more than 100 times higher than before.

The research team emphasized the significance of discovering a magnetic exciton that is not only rare but also exhibits a new quantum form. They expect this to contribute to the study of quantum phenomena in two-dimensional materials and accelerate the quantum information technology revolution. The light emitted from the exciton can be used in quantum information communication that transmits information in quantum states.

Former Deputy Director Park Jae-geun said, "Unique quantum states are very rare in two-dimensional materials," and added, "Our research team pioneered and established the field of magnetic van der Waals materials as an important research area, and once again led this field with groundbreaking research achievements."

This content was produced with the assistance of AI translation services.