The mean-field dynamics of a Bose gas is shown to break down at time $τ_h = (c_1/γ) \ln N$ where $γ$ is the Lyapunov exponent of the mean-field theory, $N$ is the number of bosons, and $c_1$ is a system-dependent constant. The breakdown time $τ_h$ is essentially the Ehrenfest time that characterizes the breakdown of the correspondence between classical and quantum dynamics. This breakdown can be well described by the quantum fidelity defined for reduced density matrices. Our results are obtained with the formalism in particle-number phase space and are illustrated with a triple-well model. The logarithmic quantum-classical correspondence time may be verified experimentally with Bose-Einstein condensates.
Quantized nonlinear transport and its breakdown in Fermi gases with Berry curvature
Key Laboratory of Quantum Materials and Devices of Ministry of Education, School of Physics, Southeast University（东南大学物理学院教育部量子材料与器件重点实验室）；Institute for Advanced Study, Tsinghua University（清华大学高等研究院）
Unconventional quantum spin mixing of two spin-1 atoms beyond the single-mode approximation
Wuhan University（武汉大学）；Hangzhou Normal University（杭州师范大学）；Hefei National Laboratory（合肥国家实验室）；Institute of Theoretical Physics, Chinese Academy of Sciences（中国科学院理论物理研究所）
Dicke superradiance in degenerate quantum matter: interplay of exchange statistics and spatial confinement
Friedrich-Alexander Universität Erlangen-Nürnberg (FAU)（埃尔朗根-纽伦堡弗里德里希·亚历山大大学）；Max Planck Institute for the Science of Light（马克斯·普朗克光科学研究所）；TU Darmstadt（达姆施塔特工业大学）
