Recently, our institute's Quantum Precision Measurement Team and Low-Dimensional Semiconductor Material Design and Device Simulation Team, in collaboration with Shanxi University, have made progress in the study of dynamical phase transitions in two-dimensional high-order topological systems. The related findings have been published in PHYSICAL REVIEW B with the title "Dynamical topological quantum phase transitions in high-order topological systems" (Phys. Rev. B 110, 064306 (2024)).

Figure 1. Dynamical phase transitions in high-order topological systems with boundary-obstructed d-wave pairing

The discovery of topological insulators and the quantum Hall effect has greatly promoted research into finding new states of matter, leading to the identification of numerous exotic topological phases. These topological phases share a common characteristic: their topological properties can be characterized by a nonlocal integer invariant, such as the Chern number. The transition between different topological phases can be represented by the discontinuous change of these topological invariants. Such equilibrium topological phase transitions have been well studied, but research into the topological characteristics exhibited by quantum systems under non-equilibrium conditions induced by nontrivial topological structures has only recently begun. The concept of dynamical phase transitions has been proposed to understand the general properties of quantum systems in non-equilibrium states. Through the study of non-equilibrium dynamical phase transitions in boundary-obstructed high-order topological systems and intrinsic high-order topological superconducting systems, we have found that dynamical phase transitions also exist in boundary-obstructed high-order topological systems, but they are not uniquely tied to the occurrence of topological phase transitions. This discovery expands the research on dynamical phase transitions in topological systems. By comparing the differences in dynamical phase transitions between boundary-obstructed high-order topological systems and intrinsic high-order topological systems, we have found that studying dynamical phase transitions can help us distinguish between different high-order topological systems without relying on the definition of specific topological invariants.

This work can expand researchers' understanding of the connection between equilibrium topological phase transitions and non-equilibrium topological phase transitions. Hefei University of Technology is the first author's institution, and Xiao Haixiao, a teacher from our institute, is the first author of the paper. Professors Li Zhongjun and Chen Bing from our institute, along with Professor Shen Heng from Shanxi University, are the corresponding authors. This work has received support from the National Key Research and Development Program, the National Natural Science Foundation of China, and the Natural Science Foundation of Anhui Province.

Article link: https://link.aps.org/doi/10.1103/PhysRevB.110.064306