Low-frequency vibration modes of biological particles, such as proteins, viruses and bacteria, involve coherent collective vibrations at frequencies in the terahertz and gigahertz domains. These vibration modes carry information on their structure and mechanical properties, which are good indicators of their biological state. In this work, we harnessed a particular regime in the physics of coupled mechanical resonators to directly measure these low-frequency mechanical resonances of a single bacterium. We deposit the bacterium on the surface of an ultrahigh frequency optomechanical disk resonator in ambient conditions. The vibration modes of the disk and bacterium hybridize when their associated frequencies are similar. We developed a general theoretical framework to describe this coupling, which allows us to retrieve the eigenfrequencies and mechanical loss of the bacterium low-frequency vibration modes (quality factor). Additionally, we analysed the effect of hydration on these vibrational modes. This work demonstrates that ultrahigh frequency optomechanical resonators can be used for vibrational spectrometry with the unique capability to obtain information on single biological entities.

中文翻译：

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单个细菌振动模式的光机械检测。

蛋白质、病毒和细菌等生物粒子的低频振动模式涉及太赫兹和千兆赫兹域频率的相干集体振动。这些振动模式携带有关其结构和机械性能的信息，这些信息是其生物状态的良好指标。在这项工作中，我们利用耦合机械共振器物理学中的特定机制来直接测量单个细菌的这些低频机械共振。我们在环境条件下将细菌沉积在超高频光机械圆盘谐振器的表面。当它们的相关频率相似时，圆盘和细菌的振动模式就会混合。我们开发了一个通用的理论框架来描述这种耦合，这使我们能够检索细菌低频振动模式（品质因数）的特征频率和机械损失。此外，我们分析了水合作用对这些振动模式的影响。这项工作表明，超高频光机械谐振器可用于振动光谱分析，具有获取单个生物实体信息的独特能力。