Low Temperature Laboratory, Aalto University School of Science, P.O. Box 15100, FI-00076 Espoo, Finland.
Nat Commun. 2012;3:987. doi: 10.1038/ncomms1993.
The coupling of distinct systems underlies nearly all physical phenomena. A basic instance is that of interacting harmonic oscillators, giving rise to, for example, the phonon eigenmodes in a lattice. Of particular importance are the interactions in hybrid quantum systems, which can combine the benefits of each part in quantum technologies. Here we investigate a hybrid optomechanical system having three degrees of freedom, consisting of a microwave cavity and two micromechanical beams with closely spaced frequencies around 32 MHz and no direct interaction. We record the first evidence of tripartite optomechanical mixing, implying that the eigenmodes are combinations of one photonic and two phononic modes. We identify an asymmetric dark mode having a long lifetime. Simultaneously, we operate the nearly macroscopic mechanical modes close to the motional quantum ground state, down to 1.8 thermal quanta, achieved by back-action cooling. These results constitute an important advance towards engineering of entangled motional states.
不同系统的耦合是几乎所有物理现象的基础。一个基本的例子是相互作用的谐振子，例如在晶格中产生声子本征模式。在混合量子系统中的相互作用尤为重要，它可以结合量子技术中每个部分的优势。在这里，我们研究了一个具有三个自由度的混合光机械系统，它由一个微波腔和两个微机械梁组成，其频率接近 32MHz，没有直接相互作用。我们记录了三方光机械混合的第一个证据，这意味着本征模式是一个光子模式和两个声子模式的组合。我们确定了一个具有长寿命的非对称暗模式。同时，我们通过反作用冷却将几乎宏观的机械模式操作到运动量子基态以下，达到 1.8 个热量子。这些结果是朝着工程纠缠运动状态迈出的重要一步。
