The rapid progress in quantum-optical experiments, especially in the field of cavity quantum electrodynamics and nanoplasmonics, allows one to substantially modify and control chemical and physical properties of atoms, molecules, and solids by strongly coupling to the quantized field. Alongside such experimental advances has been the recent development of ab initio approaches such as quantum electrodynamical density-functional theory (QEDFT), which is capable of describing these strongly coupled systems from first principles. To investigate response properties of relatively large systems coupled to a wide range of photon modes, ab initio methods that scale well with system size become relevant. In light of this, we extend the linear-response Sternheimer approach within the framework of QEDFT to efficiently compute excited-state properties of strongly coupled light–matter systems. Using this method, we capture features of strong light–matter coupling both in the dispersion and absorption properties of a molecular system strongly coupled to the modes of a cavity. We exemplify the efficiency of the Sternheimer approach by coupling the matter system to the continuum of an electromagnetic field. We observe changes in the spectral features of the coupled system as Lorentzian line shapes turn into Fano resonances when the molecule interacts strongly with the continuum of modes. This work provides an alternative approach for computing efficiently excited-state properties of large molecular systems interacting with the quantized electromagnetic field.

中文翻译：

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强耦合光物质系统的频率相关 Sternheimer 线性响应形式

量子光学实验的快速进展，特别是在腔量子电动力学和纳米等离子体激元学领域，允许人们通过与量子化场的强耦合来大幅修改和控制原子、分子和固体的化学和物理性质。除了这些实验进展之外，最近还开发了从头算方法，例如量子电动力学密度泛函理论 (QEDFT)，它能够从第一原理描述这些强耦合系统。为了研究与各种光子模式耦合的相对较大系统的响应特性，可以很好地随系统大小扩展的从头算方法变得相关。有鉴于此，我们在 QEDFT 框架内扩展了线性响应 Sternheimer 方法，以有效计算强耦合光物质系统的激发态特性。使用这种方法，我们在与腔模式强耦合的分子系统的色散和吸收特性中捕捉到强光-物质耦合的特征。我们通过将物质系统耦合到电磁场的连续体来举例说明 Sternheimer 方法的效率。我们观察到耦合系统的光谱特征的变化，因为当分子与模式的连续体强烈相互作用时，洛伦兹线形变成了法诺共振。这项工作为有效计算与量子化电磁场相互作用的大分子系统的激发态特性提供了一种替代方法。