Plasmonic quantum effects on single-emitter strong coupling
Plasmonic quantum effects on single-emitter strong coupling
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DOI：
10.1515/nanoph-2019-0199
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发表时间：
2019-10-01
期刊：
影响因子：
7.5
通讯作者：
Della Sala, Fabio
中科院分区：
文献类型：
--
作者：
Ciraci, Cristian;Jurga, Radoslaw;Della Sala, Fabio
通过减小腔模体积，可以大大增强电磁腔场与荧光分子或量子发射体之间的耦合。等离子体结构允许光限制到只有几个立方纳米的体积。在这样的长度尺度下，非局域和量子隧穿效应预计会影响发射极与表面等离子体模式的相互作用，这必然需要超越经典模型来准确描述金属表面的电子响应。在这种背景下，量子流体动力学理论（QHT）已成为一个有效的工具来探测金属纳米结构中的非局域和量子效应。在这里，我们应用最先进的QHT研究强耦合的偶极发射极放置在纳米距离的金属粒子的量子效应。通过与传统的局域响应近似（伊拉）和Fermi流体力学理论的比较，说明了量子效应对等离子体-发射极耦合的重要性。的QHT预测定性偏离LRA在弱耦合制度，导致定量的差异，在强耦合制度。在纳米带隙系统中，量子加宽的包含导致拉比分裂的最佳带隙尺寸的存在，该最佳带隙尺寸最小化对发射极振荡器强度的要求。
Coupling between electromagnetic cavity fields and fluorescent molecules or quantum emitters can be strongly enhanced by reducing the cavity mode volume. Plasmonic structures allow light confinement down to volumes that are only a few cubic nanometers. At such length scales, nonlocal and quantum tunneling effects are expected to influence the emitter interaction with the surface plasmon modes, which unavoidably requires going beyond classical models to accurately describe the electron response at the metal surface. In this context, the quantum hydrodynamic theory (QHT) has emerged as an efficient tool to probe nonlocal and quantum effects in metallic nanostructures. Here, we apply state-of-the-art QHT to investigate the quantum effects on strong coupling of a dipole emitter placed at nanometer distances from metallic particles. A comparison with conventional local response approximation (IRA) and Thomas-Fermi hydrodynamic theory results shows the importance of quantum effects on the plasmon-emitter coupling. The QHT predicts qualitative deviation from LRA in the weak coupling regime that leads to quantitative differences in the strong coupling regime. In nano-gap systems, the inclusion of quantum broadening leads to the existence of an optimal gap size for Rabi splitting that minimizes the requirements on the emitter oscillator strength.