Dynamically encircling an exceptional point for asymmetric mode switching
Dynamically encircling an exceptional point for asymmetric mode switching
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DOI：
10.1038/nature18605
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发表时间：
2016-09-01
期刊：
影响因子：
64.8
通讯作者：
Rotter, Stefan
中科院分区：
文献类型：
--
作者：
Doppler, Jorg;Mailybaev, Alexei A.;Rotter, Stefan
具有损耗或增益的物理系统具有随时间呈指数衰减或增长的谐振模式。每当两个这样的模式在它们的共振频率和它们的衰减或增长率上合并时，就会出现一个“例外点”，产生违背我们物理直觉的迷人现象（1-6）。特别有趣的行为被预测出现时，一个特殊的点是包围足够缓慢（7，8），如状态翻转或几何相位（9，10）的积累。异常点的拓扑结构已被实验探索（11-13），但此类点的完整动力学环绕以及相关的绝热性分解（14-21）仍然无法测量。在这里，我们证明了一个动态的包围一个例外的点是类似的散射通过一个双模波导适当设计的边界和损失。我们目前的实验结果从相应的波导结构，引导入射波在传输过程中的一个例外点周围。以这种方式，引起模式转变，其将该器件转变为不同波导模式之间的鲁棒且不对称的开关。这项工作将使探索特殊点物理系统控制和状态转移计划之间的基础研究和实际应用的十字路口。
Physical systems with loss or gain have resonant modes that decay or grow exponentially with time. Whenever two such modes coalesce both in their resonant frequency and their rate of decay or growth, an 'exceptional point' occurs, giving rise to fascinating phenomena that defy our physical intuition(1-6). Particularly intriguing behaviour is predicted to appear when an exceptional point is encircled sufficiently slowly(7,8), such as a state-flip or the accumulation of a geometric phase(9,10). The topological structure of exceptional points has been experimentally explored(11-13), but a full dynamical encircling of such a point and the associated breakdown of adiabaticity(14-21) have remained out of reach of measurement. Here we demonstrate that a dynamical encircling of an exceptional point is analogous to the scattering through a two-mode waveguide with suitably designed boundaries and losses. We present experimental results from a corresponding waveguide structure that steers incoming waves around an exceptional point during the transmission process. In this way, mode transitions are induced that transform this device into a robust and asymmetric switch between different waveguide modes. This work will enable the exploration of exceptional point physics in system control and state transfer schemes at the crossroads between fundamental research and practical applications.