Dicke-enhanced single-emitter strong coupling at ambient conditions as a quantum resource

光和物质在单发射体水平上的强耦合是一种基本的量子资源，因为它提供了(I)单光子和二能级系统之间确定性的能量交换，以及(Ii)通过Jaynes-Cummings阶梯的非谐性实现单光子非线性的可能性。我们最近展示了在室温和环境条件下量子点和宽带等离子体纳米谐振器的强耦合，为了解释这些结果，假设的宽带多能级耦合导致了单发射体耦合强度的Dicke式增强以及量子发射体与等离子体纳米谐振器的增强耦合。在目前的项目中，这两种猜想都将受到仔细的审查，并被带入量子资源。为此，我们将开发一个在表面上集成强耦合量子发射体-等离子体纳米共振器系统的平台。介电将被用来利用电连接的等离子体纳米结构在所需位置整合量子点，例如等离子体热点-这是我们中的一位首创的技术进步。这种纳米结构的另一个优点是有可能在量子发射器上施加非常大的直流电场，这将被用来通过量子受限斯塔克效应引入可调性。为了实验上实现Dicke式的耦合强度增强，我们将使用PbS或PbSe量子点，它们提供高达的接近量子点导带边缘的简并能级。这应该会将耦合强度增加近一个数量级，从而放宽制造公差。核壳胶体量子点将以尽可能高的质量制备，并控制表面化学，以便进行单发射极实验。在理论方面，我们将发展一种新的方法，在纳米尺度上研究光物质的量子光学耦合，该方法考虑了等离子体纳米谐振器的准正交模结构，并考虑了它们在宽带光物质相互作用中的作用。我们的结果将带来一种方法学，将在单发射体的基础上建立强的、甚至可能超强的光-物质相互作用，作为一种新的量子资源。由于增加了耦合，大大降低了制造公差，这将大大提高可获得性。量子多准简正模理论将为准确预测这些极端条件下的量子光物质动力学提供一个完整的理论框架，并将有助于量子信息处理和量子传感器件的实验实现。具体地说，作为最终目标，我们提出了一种基于可扩展体系结构的纳米级单光子晶体管的实现和表征。

Strong coupling of light and matter at the single emitter level is a fundamental quantum resource since it offers (i) deterministic energy exchange between single photons and a two-level system, and (ii) the possibility to achieve single-photon nonlinearities via the anharmonicity of the Jaynes-Cummings ladder. We recently demonstrated strong coupling of a quantum dot and a broadband plasmonic nanoresonator at room temperature and ambient conditions and, to explain these results, postulated broadband multilevel coupling leading to a Dicke-type enhancement of the single-emitter coupling strength as well as enhanced coupling of the quantum emitter to the plasmonic nanoresonator. In the present project, both conjectures will be put under scrutiny and carried forward towards a quantum resource. To do so, we will develop a platform to integrate strongly coupled quantum emitter - plasmonic nanoresonator systems on a surface. Dielectrophoresis will be used to integrate quantum dots at desired positions, such as plasmonic hotspots, using electrically connected plasmonic nanostructures - a technological advance that was pioneered by one of us. An additional advantage of such nanostructures is the possibility to apply very large DC electric fields to quantum emitters which will be used to introduce tunability via the quantum confined Stark-effect. To experimentally achieve a Dicke-type enhancement of the coupling strength we will use PbS or PbSe quantum dots that offer up to 64 nearly degenerate levels close to the conduction band edge of a quantum dot. This should increase the coupling strength by nearly one order of magnitude thereby relaxing fabrication tolerances. Core-shell colloidal quantum dots will be prepared at the highest possible quality with controlled surface chemistry such that single-emitter experiments can be performed. On the theoretical side, we will develop a new approach to the quantum optics of light matter coupling at the nanoscale that takes into account the quasinormal mode structure of plasmonic nanoresonators and considers their role in broadband light matter interactions. Our results will lead to a methodology that will establish strong and possibly ultrastrong light-matter interaction at the single emitter basis as a novel quantum resource. Accessibility will be strongly enhanced by the largely reduced fabrication tolerances that should become affordable because of the increased coupling. The quantum multi-quasi-normal mode theory will provide a complete theoretical framework to accurately predict quantum light-matter dynamics at these extreme conditions and will aid the experimental implementation of devices for quantum information processing and quantum sensing. Specifically, as a final goal, we propose the implementation and characterization of a nanoscale single-photon transistor based on a scalable architecture.