近日，捷克科学院科学仪器研究所的Oto Brzobohatý&Stephen H. Simpson及其研究团队取得一项新进展。经过不懈努力，他们揭示真空中悬浮非互易耦合光机械振子的类PT相变和极限环振荡。相关研究成果已于2024年7月25日在国际知名学术期刊《自然—物理学》上发表。

该研究团队证明了一对非保守耦合振子的集体非厄米动力学。研究人员利用了系统中粒子间光相互作用的可调性，并将粒子间的光相互作用设置为纯非互易。通过连续改变捕获光束的相对功率，研究人员使系统经历了类似于宇称时间相变的转变。

在临界点处的Hopf分岔导致集体极限环振荡的形成，类似于在声子激光器中观察到的那些。这些耦合悬浮振荡器为特殊的点光机械传感提供了一个平台，并且可以扩展到多粒子系统，为拓扑光机械介质的发展铺平了道路。

据悉，悬浮于光学阱中的纳米粒子提供了一个多功能平台，可用于在具有可调参数的受控环境中研究机械振荡器。近期，人们已成功实现了将两个这样的光机械振荡器进行耦合。

附：英文原文

Title: PT-like phase transition and limit cycle oscillations in non-reciprocally coupled optomechanical oscillators levitated in vacuum

Author: Lika, Vojtch, Zemnkov, Tereza, Jkl, Petr, iler, Martin, Simpson, Stephen H., Zemnek, Pavel, Brzobohat, Oto

Issue&Volume: 2024-07-25

Abstract: Nanoparticles levitated in an optical trap provide a versatile platform to study mechanical oscillators in a controlled environment with tuneable parameters. Recently, it has become possible to couple two of these optomechanical oscillators. Here we demonstrate the collective non-Hermitian dynamics of such a pair of non-conservatively coupled oscillators. We take advantage of the tunability of the optical interactions between the particles in our system and set the optical interaction between the particles to be purely non-reciprocal. By continuously varying the relative power of the trapping beams, we take the system through a transition similar to a parity–time phase transition. A Hopf bifurcation at a critical point results in the formation of collective limit cycle oscillations, resembling those observed in phonon lasers. These coupled levitated oscillators provide a platform for exceptional point optomechanical sensing and can be extended to multi-particle systems, paving the way for the development of topological optomechanical media.

DOI: 10.1038/s41567-024-02590-1

Source: https://www.nature.com/articles/s41567-024-02590-1