Light-Matter Response in Nonrelativistic Quantum Electrodynamics
Light-Matter Response in Nonrelativistic Quantum Electrodynamics
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DOI：
10.1021/acsphotonics.9b00768
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发表时间：
2019-11-01
期刊：
影响因子：
7
通讯作者：
Rubio, Angel
中科院分区：
文献类型：
--
作者：
Flick, Johannes;Welakuh, Davis M.;Rubio, Angel
我们导出了长波极限下非相对论量子电动力学的全线性响应理论，并提供了一个实用的框架来利用量子电动力学密度泛函理论求解所得到的方程。我们强调了量子化光和物质之间的耦合如何改变通常的响应函数，并引入了交叉相关的光-物质响应函数。由于量子物质介导的光子-光子相互作用，这些互相关响应导致麦克斯韦方程组的可测量变化。处理组合物质-光子响应的关键特征是，激发的自然寿命可以直接从第一性原理获得，由于强光-物质耦合而引起的电子结构变化被完全非摄动地处理，并且考虑了物质与光子真空反作用的自洽解，反之亦然。通过引入耦合物质-光子问题的随机相位近似的直接扩展，我们计算了与量子化电磁场耦合的真实分子系统的从头算谱。我们的方法可以非常有效地进行数值求解。所提出的框架通过强调电子激发态如何作为光子场的修改而产生，以及实验观察到的效应总是由于光与物质之间复杂的相互作用而导致范式的转变。同时，这些发现为量子化学、纳米等离子体学和量子光学之间的界面提供了分析和提出实验的途径。
We derive the full linear-response theory for nonrelativistic quantum electrodynamics in the long wavelength limit and provide a practical framework to solve the resulting equations by using quantum-electrodynamical density-functional theory. We highlight how the coupling between quantized light and matter changes the usual response functions and introduces cross-correlated light-matter response functions. These cross-correlation responses lead to measurable changes in Maxwell's equations due to the quantum-matter-mediated photon-photon interactions. Key features of treating the combined matter-photon response are that natural lifetimes of excitations become directly accessible from first-principles, changes in the electronic structure due to strong light-matter coupling are treated fully nonperturbatively, and self-consistent solutions of the back-reaction of matter onto the photon vacuum and vice versa are accounted for. By introducing a straightforward extension of the random-phase approximation for the coupled matter-photon problem, we calculate the ab initio spectra for a real molecular system that is coupled to the quantized electromagnetic field. Our approach can be solved numerically very efficiently. The presented framework leads to a shift in paradigm by highlighting how electronically excited states arise as a modification of the photon field and that experimentally observed effects are always due to a complex interplay between light and matter. At the same time the findings provide a route to analyze as well as propose experiments at the interface between quantum chemistry, nanoplasmonics and quantum optics.