Quantum Materials Modeling Group｜Research Center for Materials Nanoarchitectonics

About Quantum Materials Modeling Group

Mission of Quantum Properties Modeling Group

We theoretically analyze and design quantum information carriers, such as charge, spin, composite excitations, and fractionalized particles, embedded in quantum materials that serve as the “building materials” for nanoarchitectonics.
We further elucidate the material phases that emerge from the interactions and quantum entanglement of these information carriers, as well as the mechanisms underlying their formation. By incorporating concepts and methods from quantum information science and quantum computing into materials science, we aim to advance the understanding, prediction, and design of quantum materials, while exploring their potential to realize new quantum-information functionalities. Through these efforts, we seek to establish new design principles for quantum materials and expand our research toward collaborations in quantum information science, quantum computing, and device applications.

Research Overview

Matter containing many confined electrons exhibits properties fundamentally different from those of a single isolated electron in vacuum. In the Quantum Properties Modeling Group, we have explored novel functionalities emerging from many-electron systems by integrating first-principles electronic-structure calculations for quantum condensed matter, statistical and statistical-mechanical approaches including machine learning, and field-theoretical methods. We are particularly interested in “quantum-entangled materials,” in which non-trivial quantum entanglement among electrons gives rise to properties that go beyond the conventional single-particle picture.

In recent years, we have been pursuing theoretical studies of magnetic and electrical responses arising from the interplay among electron spin, orbital degrees of freedom, and crystal structure. We have also been devoted to the development of first-principles computational methods, as well as computational and data-science approaches for extracting the electronic properties of quantum materials from spectroscopic experiments.

For example, we investigate altermagnets, which exhibit spin-split electronic structures despite having no macroscopic magnetization, with the aim of establishing materials-design principles that could lead to novel spintronic functionalities [1]. We have also studied the microscopic mechanisms underlying multiferroicity, in which electric polarization is coupled with spin configurations, and have worked toward the theoretical design of rare materials that exhibit both ferromagnetism and ferroelectricity [2].

We are also developing first-principles approaches and new computational methods for quantum-entangled materials using the Fugaku supercomputer. With a particular focus on high-critical-temperature cuprate superconductors, the family of materials exhibiting the highest superconducting transition temperatures at ambient pressure, we are developing numerical methods based on many-body wave functions incorporating artificial neural networks. Using these approaches, we seek to elucidate superconducting states at zero temperature and theoretically analyze spectroscopic signatures observed in photoemission spectroscopy, scanning tunneling spectroscopy, and inelastic neutron and X-ray scattering.

The integration of experiment and data science is another major focus of our research. We have developed photoemission microscopy tomography, which reconstructs the crystallographic orientation and electronic structure of individual grains from large volumes of spectroscopic data obtained by photoemission microscopy on polycrystalline samples. This approach aims to extend electronic-structure analysis, which has conventionally relied on single crystals, to polycrystalline materials [3]. We are also pioneering machine-learning spectroscopy, in which artificial neural networks are used to extract information about the underlying electron-electron interactions from complex photoemission and tunneling spectra of high-critical-temperature cuprate superconductors [4].

Through these efforts, we promote a bidirectional approach to quantum-materials research. We aim not only to predict physical properties from theory but also to decode quantum states and many-body interactions in materials from experimental data. Furthermore, we regard charge, spin, composite excitations, and fractionalized particles as quantum information carriers in materials. By understanding and designing the emergent phases and novel functionalities arising from their interactions and quantum entanglement, we aim to discover new functionalities in quantum materials that can lead to applications in quantum information, quantum computing, and energy-efficient devices.

Recent Publications

Research Fields

Quantum spin liquids and emergent entanglement structures
Topological phases of matter and their quantum functions
Theoretical and Monte Carlo studies on low-dimensional quantum magnets
Realistic modeling of electronic and magnetic properties using first-principles electronic structure calculations
Magnetism of two-dimensional van der Waals materials
Microscopic theories of magnetoelectric coupling induced by complex magnetic order
Novel theoretical and numerical schemes to investigate classical and quantum phase transitions