Recently, a team led by Prof. Jia Laitang, Prof. Xiao Liantuan and Prof. Mei Feng from the Institute of Laser Spectroscopy of Shanxi University has made important progress in the research of topological states. The research result "Dynamical Detection of Topological Spec...
Recently, a team led by Prof. Jia Laitang, Prof. Xiao Liantuan and Prof. Mei Feng from the Institute of Laser Spectroscopy, Shanxi University has made important progress in the study of topological states. The research result "Dynamical Detection of Topological Spectral Density" was published in Physical Review Letters on Jan. 17, 2012, which was done independently by Shanxi University, and Dr. Jiahui Zhang, a doctoral student of Institute of Laser Spectroscopy, was the first author of the paper. Dr. Zhang Jiahui was the first author of the paper, Prof. Mei Feng was the corresponding author, and Prof. Jia Laitang and Prof. Xiao Liantuan provided important guidance.
Topological states are a kind of brand-new states associated with topology, with natural topology-preserving robustness to internal rise and fall and external perturbation of the system, and have very important applications in the fields of material science, quantum information and quantum precision measurement. A key scientific question is how to identify topological matter state materials. The presence or absence of topological boundary states is the main method to identify topological material states. Currently, the latest international progress is to identify the existence of topological boundary states by probing the local state density. However, the detection of topological localized state density is still a difficult problem, especially in periodically driven nonequilibrium topological systems.
(1-4) Schematic diagram of the principle:Dynamical detection of equilibrium and nonequilibrium topological localized state densities.
(5-14) Application example: non-equilibrium topological localized density of states identifies mediocre and non-mediocre higher-order topological states that are indistinguishable on the energy spectrum.
For the first time, the research team finds a concise and beautiful physical connection between chiral quantum dynamics and Loschmidt echoes, i.e., the Loschmidt amplitude at moment t is equal to the center of chirality at moment t/2. Using this physical connection, the team further found that chiral quantum dynamics can directly probe the topological localized density of states. The method is powerful enough to reveal both the energy spectrum and the topological properties of the spatial distribution of topological boundary states. The method is also universal and can be applied not only to static equilibrium topological systems but also to periodically driven nonequilibrium topological systems. The research team demonstrates that the density of localized states of nonequilibrium topology can directly probe and reveal the unique topological properties of nonequilibrium topological states, including the quasi-energy spectrum and topological modes of periodic topology, which provides a new means of nonequilibrium topology probing.
This research is supported by the Key Research and Development Program of the Ministry of Science and Technology, the National Natural Science Foundation of China, the Key Discipline Construction Fund of Shanxi Province's "1331" Project, the State Key Laboratory of Quantum Optics and Optical Quantum Devices, and the Collaborative Innovation Center for Extreme Optics jointly established by the Ministry of Science and Technology of China and the Ministry of Science and Technology of the People's Republic of China.
