Mondal Debabrata, Sinha Sudip, Sinha S
Indian Institute of Science Education and Research-Kolkata, Mohanpur, Nadia-741246, India.
Phys Rev E. 2022 Jan;105(1-1):014130. doi: 10.1103/PhysRevE.105.014130.
We consider an interacting collective spin model known as coupled top (CT), exhibiting a rich variety of phenomena related to quantum transitions, ergodicity, and formation of quantum scars, discussed in our previous work [Mondal, Sinha, and Sinha, Phys. Rev. E 102, 020101(R) (2020)2470-004510.1103/PhysRevE.102.020101]. In this work, we present a detailed analysis of the different type of transitions in the CT model, and find their connection with the underlying collective spin dynamics. Apart from the quantum scarring phenomena, we also identify another source of deviation from ergodicity due to the presence of nonergodic multifractal states. The degree of ergodicity of the eigenstates across the energy band is quantified from the relative entanglement entropy as well as multifractal dimensions, which can be probed from nonequilibrium dynamics. Finally, we discuss the detection of nonergodic behavior and different types of quantum scars using "out-of-time-order correlators," which has relevance in the recent experiments.
我们考虑一种被称为耦合陀螺（CT）的相互作用集体自旋模型，它展现出了与量子跃迁、遍历性以及量子疤痕形成相关的丰富多样的现象，这些在我们之前的工作[蒙达尔、辛哈和辛哈，《物理评论E》102，020101(R) (2020)2470 - 004510.1103/PhysRevE.102.020101]中有所讨论。在这项工作中，我们对CT模型中不同类型的跃迁进行了详细分析，并发现了它们与潜在集体自旋动力学的联系。除了量子疤痕现象，我们还识别出由于非遍历多重分形态的存在而导致的另一种偏离遍历性的来源。通过相对纠缠熵以及多重分形维数对整个能带本征态的遍历程度进行了量化，这可以从非平衡动力学中探测到。最后，我们讨论了使用“时间反序关联函数”来检测非遍历行为和不同类型的量子疤痕，这在近期的实验中具有相关性。
