The research team has made progress in the study of in the detection of non-equilibrium topological states Phys. Rev. Lett. 132, 036603 (2024).
Recently, the team led by Professor Jia Suotang, Professor Xiao Liantuan, and Professor Mei Feng from the Institute of Laser Spectroscopy has made significant progress in the study of topological states. The related research results Dynamical Detection of Topological Spectral Density were published in Physical Review Letters on January 17th. This work was independently completed by Shanxi University, with my doctoral student Zhang Jiahui as the first author of the paper, Professor Mei Feng as the corresponding author, and Professor Jia Suotang and Professor Xiao Liantuan providing important guidance.
Topological states are a new type of state related to topology, which have natural topological protection robustness against internal fluctuations and external disturbances in the system. They have significant application value in the fields of materials science, quantum information, and quantum precision measurement. A key scientific question is how to identify topological materials. The existence of topological boundary states is the main method for identifying topological states. At present, the latest progress internationally is to identify the existence of topological boundary states by detecting local density of states. However, the detection of topological local density of states remains a challenging problem, especially in periodically driven non-equilibrium topological systems.
Fig.1|(a-d) Schematic diagram: Dynamics detection of equilibrium and non-equilibrium topological local density of states. (e-j) Application example: Non equilibrium topology local state density identification of indistinguishable ordinary and non ordinary high-order topological states on the energy spectrum
The research team has discovered for the first time a concise and elegant physical connection between chiral quantum dynamics and Loschmidt echoes, that is, the amplitude of Loschmidt at time t is equal to the chiral center at time t/2. Using this physical connection, the research team further discovered that chiral quantum dynamics can directly detect topological localized density of states. This method is powerful and can simultaneously reveal the energy spectrum and spatial distribution topological characteristics of topological boundary states. This method also has universality, not only applicable to statically balanced topology systems, but also to periodically driven non-equilibrium topology systems. The research team has demonstrated that the local density of states in non-equilibrium topology can directly detect and reveal the unique topological characteristics of non-equilibrium topological states, including periodic topological quasi spectra and topological patterns, providing a new means for non-equilibrium topology detection.
The research was 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 the "1331" Project in Shanxi Province, the State Key Laboratory of Quantum Optics and Optical Quantum Devices, and the provincial and ministerial collaborative innovation center for extreme optics.
