Physical systems with gain and loss can be described by a non-Hermitian Hamiltonian, which is degenerated at the exceptional points (EPs). Many new and unexpected features have been explored in the non-Hermitian systems with a great deal of recent interest. One of the most fascinating features is that, chiral state conversion appears when one EP is encircled dynamically. Here, we propose an easy-controllable levitated microparticle system that carries a pair of EPs and realize slow evolution of the Hamiltonian along loops in the parameter plane. Utilizing the controllable rotation angle, gain and loss coefficients, we can control the structure, size and location of the loops in situ. We demonstrate that, under the joint action of topological structure of energy surfaces and nonadiabatic transitions (NATs), the chiral behavior emerges both along a loop encircling an EP and even along a straight path away from the EP. This work broadens the range of parameter space for the chiral state conversion, and proposes a useful platform to explore the interesting properties of exceptional points physics.

中文翻译：

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具有参数环原位控制的悬浮微机械振荡器中的手性状态转换

具有增益和损耗的物理系统可以用非厄米哈密顿量来描述，它在异常点 (EP) 处退化。在非厄米系统中探索了许多新的和意想不到的特征，最近引起了极大的兴趣。最令人着迷的特点之一是，当动态包围一张EP时，会出现手性状态转换。在这里，我们提出了一种易于控制的悬浮微粒系统，该系统携带一对 EP 并实现哈密顿量沿参数平面中的循环缓慢演化。利用可控的旋转角度、增益和损耗系数，我们可以就地控制回路的结构、大小和位置。我们证明，在能量面拓扑结构和非绝热跃迁（NATs）的共同作用下，手性行为沿着围绕 EP 的环出现，甚至沿着远离 EP 的直线路径出现。这项工作拓宽了手性状态转换的参数空间范围，并提出了一个有用的平台来探索异常点物理的有趣特性。