论文标题
在椭圆旋转场的影响下的自旋动力学：从时间平均数量中提取场拓扑
Spin dynamics under the influence of elliptically rotating fields: Extracting the field topology from time-averaged quantities
论文作者
论文摘要
我们专注于量子系统，可以有效地将其描述为局部旋转的粒子粒子，约有静态磁场的固定磁场，以与共存的椭圆形旋转的时间周期性场。根据静态和旋转组件所取的值，总磁场显示了具有不同拓扑特性的两个机制。沿着这两个方案分开的边界，总磁场会在时间上定期消失，并且系统动力学变得高度无绝热。我们得出了两个时间平均数量的系统之间的关系，该系统与应用磁场的拓扑相关。基于这一发现，我们提出了一个可测量的数量，该数量具有指示总磁场拓扑的能力，而又不知道静态分量的值。我们还建议通过被困的离子量子系统对我们的方法进行实施。此处介绍的结果与系统的初始状态无关。特别是，当系统以浮雕状态初始化时，我们发现了与总磁场的拓扑变化相关的胶质光谱的一些有趣属性。在整篇文章中，通过数值模拟进行了两级量子系统的数值模拟来说明理论结果。
We focus on quantum systems that can be effectively described as a localized spin-$s$ particle subject to a static magnetic field coplanar to a coexisting elliptically rotating time-periodic field. Depending on the values taken on by the static and rotating components, the total magnetic field shows two regimes with different topological properties. Along the boundary that separates these two regimes, the total magnetic field vanishes periodically in time and the system dynamics becomes highly nonadiabatic. We derive a relation between two time-averaged quantities of the system which is linked to the topology of the applied magnetic field. Based on this finding, we propose a measurable quantity that has the ability to indicate the topology of the total magnetic field without knowing a priori the value of the static component. We also propose a possible implementation of our approach by a trapped-ion quantum system. The results presented here are independent of the initial state of the system. In particular, when the system is initialized in a Floquet state, we find some interesting properties of the quasienergy spectrum which are linked to the topological change of the total magnetic field. Throughout the paper, the theoretical results are illustrated with numerical simulations for the case of a two-level quantum system.
