Observation of Anti-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:mrow><mml:mi mathvariant="script">P</mml:mi><mml:mi mathvariant="script">T</mml:mi></mml:mrow></mml:math>-Symmetry Phase Transition in the Magnon-Cavity-Magnon Coupled System
Jie Zhao, Yulong Liu, Longhao Wu, Chang‐Kui Duan, Yu-xi Liu, Jiangfeng Du
Abstract
As the counterpart of $\mathcal{P}\mathcal{T}$ symmetry, for anti-$\mathcal{P}\mathcal{T}$-symmetry abundant phenomena and potential applications have been predicted or demonstrated theoretically. However, experimental realization of the coupling required in anti-$\mathcal{P}\mathcal{T}$ symmetry is difficult. By our coupling two yttrium iron garnet spheres commonly to a microwave cavity, the large cavity dissipation rate makes the magnon-magnon coupling dissipative and purely imaginary. Thereby, the hybrid magnon-cavity system obeys a two-dimensional anti-$\mathcal{P}\mathcal{T}$ Hamiltonian. In terms of the magnon-readout method, the method adopted here, we demonstrate the validity of our method in constructing an anti-$\mathcal{P}\mathcal{T}$ system and present the counterintuitive level-attraction process. Our work provides a platform to explore the anti-$\mathcal{P}\mathcal{T}$-symmetry properties and paves the way to study dynamical evolution and topological properties around exceptional points in multimagnon-cavity systems.