Xiang Yuan

Scientific laws present fundamental differences in different dimensions. For example, gravity is inversely proportional to the square of distance in 3D space, but in 2D space, gravity will be inversely proportional to distance, and in 1D space, gravity does not change with distance​​.

The exploration of the scientific laws of elementary particles in different dimensions is one of the fundamental scientific problems, but relatively difficult to solve in experiments. Xiang Yuan has been engaged in research on these challenges for a long time. In this regard, he overcame the difficulties of infrared compatibility, proposed and implemented an alternative approach to carry out infrared spectroscopy under high magnetic field, providing an important technical foundation for exploring strong magnetic field scientific problems. With the help of the novel magnetic infrared measurement technology, Xiang Yuan constructed new dimensional topological quasiparticles (such as Weyl Fermions) under strong magnetic fields and discovered 1D Weyl Fermions. He used 35T strong magnetic field and performed magneto-infrared spectroscopy to track the change of optical transition activity between Landau energy levels and found that topological insulators have undergone three topological phase transitions under strong magnetic fields. The zeroth Landau band crosses under a strong magnetic field and triggers a topological Lifshitz phase transition. Based on this evidence, he successfully discovered the 1D Weyl Fermions and detected its unique divergence in optical absorption.

Xiang Yuan also discovered the 3D quantum Hall effect. The quantum Hall effect has been one of the most important discoveries in the field of condensed matter physics since the 20th century and was believed to exist only in 2D systems. He presents experimental evidence of the 3D quantum Hall effect, breaking the conventional perception that the quantum Hall effect can only exist in 2D systems.