The light-matter interaction can be utilized to qualitatively alter physical properties of materials. Recent theoretical and experimental studies have explored this possibility of controlling matter by light based on driving many-body systems via strong classical electromagnetic radiation, leading to a time-dependent Hamiltonian for electronic or lattice degrees of freedom. To avoid inevitable heating, pump-probe setups with ultrashort laser pulses have so far been used to study transient light-induced modifications in materials. Here, we pursue yet another direction of controlling quantum matter by modifying quantum fluctuations of its electromagnetic environment. In contrast to earlier proposals on light-enhanced electron-electron interactions, we consider a dipolar quantum many-body system embedded in a cavity composed of metal mirrors, and formulate a theoretical framework to manipulate its equilibrium properties on the basis of quantum light-matter interaction. We analyze hybridization of different types of the fundamental excitations, including dipolar phonons, cavity photons, and plasmons in metal mirrors, arising from the cavity confinement in the regime of strong light-matter interaction. This hybridization qualitatively alters the nature of the collective excitations and can be used to selectively control energy-level structures in a wide range of platforms. Most notably, in quantum paraelectrics, we show that the cavity-induced softening of infrared optical phonons enhances the ferroelectric phase in comparison with the bulk materials. Our findings suggest an intriguing possibility of inducing a superradiant-type transition via the light-matter coupling without external pumping. We also discuss possible applications of the cavity-induced modifications in collective excitations to molecular materials and excitonic devices.

中文翻译：

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物质的量子电动力学控制：腔增强铁电相变

光-物质相互作用可用于定性改变材料的物理性质。最近的理论和实验研究已经探索了通过强古典电磁辐射驱动多体系统，从而通过光控制物质的可能性，从而导致了电子或晶格自由度的时变哈密顿量。为了避免不可避免的加热，迄今为止，具有超短激光脉冲的泵浦探针装置已用于研究材料中瞬态光引起的改性。在这里，我们追求通过改变其电磁环境的量子涨落来控制量子物质的另一个方向。与先前有关光增强电子-电子相互作用的提议相反，我们认为嵌入在由金属镜组成的腔中的双极量子多体系统，并建立了一个基于量子光-物质相互作用来操纵其平衡性质的理论框架。我们分析了不同类型的基本激发的杂交，包括偶极子声子，腔体光子和金属镜中的等离激元，它们是由强光-质相互作用的腔体限制引起的。这种杂交从质上改变了集体激发的性质，可用于选择性地控制各种平台上的能级结构。最值得注意的是，在量子顺电中，我们表明，与块状材料相比，腔体诱导的红外光子的软化增强了铁电相。我们的发现表明，在没有外部泵浦的情况下，通过光-质耦合引起超辐射型跃迁的可能性非常诱人。我们还讨论了在分子材料和激子器件的集体激发中腔诱导修饰的可能应用。