Joint Laboratory of Optics of Palacký University and Institute of Physics of CAS, Faculty of Science, Palacký University, 17. listopadu 12, 771 46, Olomouc, Czech Republic.
Theoretical Quantum Physics Laboratory, Cluster for Pioneering Research, RIKEN, Wako-shi, Saitama, 351-0198, Japan.
Nat Commun. 2023 Apr 12;14(1):2076. doi: 10.1038/s41467-023-37275-5.
Nontrivial spectral properties of non-Hermitian systems can lead to intriguing effects with no counterparts in Hermitian systems. For instance, in a two-mode photonic system, by dynamically winding around an exceptional point (EP) a controlled asymmetric-symmetric mode switching can be realized. That is, the system can either end up in one of its eigenstates, regardless of the initial eigenmode, or it can switch between the two states on demand, by simply controlling the winding direction. However, for multimode systems with higher-order EPs or multiple low-order EPs, the situation can be more involved, and the ability to control asymmetric-symmetric mode switching can be impeded, due to the breakdown of adiabaticity. Here we demonstrate that this difficulty can be overcome by winding around exceptional curves by additionally crossing diabolic points. We consider a four-mode [Formula: see text]-symmetric bosonic system as a platform for experimental realization of such a multimode switch. Our work provides alternative routes for light manipulations in non-Hermitian photonic setups.
非厄米系统的非平凡谱性质可能导致在厄米系统中没有对应物的有趣效应。例如，在一个双模光子系统中，通过动态环绕一个异常点（EP），可以实现受控的非对称-对称模式切换。也就是说，无论初始本征模如何，系统最终都可以处于其本征态之一，或者可以通过简单地控制缠绕方向按需在两种状态之间切换。然而，对于具有高阶 EP 或多个低阶 EP 的多模系统，情况可能更加复杂，由于绝热性的破坏，控制非对称-对称模式切换的能力可能会受到阻碍。在这里，我们通过额外穿过恶魔点来环绕异常曲线，证明了可以克服这一困难。我们考虑一个四模[公式：见文本]-对称玻色系统作为在实验中实现这种多模开关的平台。我们的工作为非厄米光子设备中的光操纵提供了替代途径。
