Observation of exceptional points in magnonic parity-time symmetry devices
Observation of exceptional points in magnonic parity-time symmetry devices
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DOI：
10.1126/sciadv.aax9144
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发表时间：
2019-11-01
期刊：
影响因子：
13.6
通讯作者：
Vardeny, Z. Valy
中科院分区：
文献类型：
--
作者：
Liu, Haoliang;Sun, Dali;Vardeny, Z. Valy
非厄米哈密顿仍然可以有真实的本征值，只要存在组合的宇称-时间（PT）对称性。PT对称性的前景已经在光子学、声学和电子学等物理系统中得到了探索。在这些系统中的特征值经历了从真实的过渡到复杂的例外点（EP），PT对称性被打破。在这里，我们证明了存在EP的两个耦合磁体组成的磁振子的设备具有不同的磁振子损失。随着耦合强度的增加，本征频率和阻尼率在EP处由交叉变为反交叉。磁振子色散包括强的“类声”模和弱的“类光”模。此外，在微波辐射时，PT磁振子装置充当磁振子谐振腔，与常规磁振子系统相比具有独特的响应。
Non-Hermitian Hamiltonians may still have real eigenvalues, provided that a combined parity-time (PT) symmetry exists. The prospect of PT symmetry has been explored in several physical systems such as photonics, acoustics, and electronics. The eigenvalues in these systems undergo a transition from real to complex at exceptional points (EPs), where the PT symmetry is broken. Here, we demonstrate the existence of EP in magnonic devices composed of two coupled magnets with different magnon losses. The eigenfrequencies and damping rates change from crossing to anti-crossing at the EP when the coupling strength increases. The magnonic dispersion includes a strong "acoustic-like" mode and a weak "optic-like" mode. Moreover, upon microwave radiation, the PT magnonic devices act as magnon resonant cavity with unique response compared to conventional magnonic systems.