Achieving control over light–matter interaction in custom-tailored nanostructures is at the core of modern quantum electrodynamics. In strongly and ultrastrongly coupled systems, the excitation is repeatedly exchanged between a resonator and an electronic transition at a rate known as the vacuum Rabi frequency Ω_R. For Ω_R approaching the resonance frequency ω_c, novel quantum phenomena including squeezed states, Dicke superradiant phase transitions, the collapse of the Purcell effect, and a population of the ground state with virtual photon pairs are predicted. Yet, the experimental realization of optical systems with Ω_R/ω_c ≥ 1 has remained elusive. Here, we introduce a paradigm change in the design of light–matter coupling by treating the electronic and the photonic components of the system as an entity instead of optimizing them separately. Using the electronic excitation to not only boost the electronic polarization but furthermore tailor the shape of the vacuum mode, we push Ω_R/ω_c of cyclotron resonances ultrastrongly coupled to metamaterials far beyond unity. As one prominent illustration of the unfolding possibilities, we calculate a ground state population of 0.37 virtual photons for our best structure with Ω_R/ω_c = 1.43 and suggest a realistic experimental scenario for measuring vacuum radiation by cutting-edge terahertz quantum detection.

中文翻译：

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太赫兹光-物质相互作用超出了单元耦合的强度

在定制的纳米结构中实现对光-质相互作用的控制是现代量子电动力学的核心。在强和ultrastrongly耦合的系统中，激励被重复的谐振器，并在被称为真空拉比频率Ω的速率的电子跃迁之间交换_ř。为Ω _ř接近的谐振频率ω _{c ^}，新颖量子现象，包括压缩态，迪克超辐射相变，的赛尔效果崩溃，并用虚光子对基态的群体进行预测。然而，光学系统的实验实现与Ω _{- [R} /ω _Ç≥1仍然难以捉摸。在这里，我们通过将系统的电子和光子组件视为一个实体，而不是分别对其进行优化，从而在光-质耦合设计中引入了一种范式变化。使用电子激发不仅提高电子极化而且此外裁缝真空模式的形状，我们推Ω _{- [R} /ω _Ç ultrastrongly耦合到超材料远远超出统一回旋加速器共振。作为展开可能性之一突出说明，我们计算的0.37虚拟光子的基态人口与Ω我们的最佳结构_{- [R} /ω _{c ^} = 1.43，并提出用于通过前沿太赫兹量子检测的测量真空辐射一个现实的实验方案。