Polariton-based single-photon sources

具有特殊性质的单光子是量子光学、通信、计算和计量学的基本资源。然而，创建这些光子状态并不是完全简单的，虽然有各种方法可以实现这一点，但它们都受到所需设置的复杂性或系统难以扩展的事实的影响。因此，一个实际可行的实施方案仍然缺乏。在这个方案中，我们想要通过实验研究微腔极化子系统来解决这个问题，微腔极化子系统是限制在短腔中的光子和量子井激子的相干叠加。当极化子衰变时，就会产生一个飞行的光子。一些理论工作已经讨论了极化子产生量子关联光子的潜力，并且已经有几个量子效应的实验演示，例如一阶关联和压缩。与依赖单个量子发射器实现的方案相比，极化系统的最大优势是其固有的可扩展性、健壮性和定制特定属性的可能性，如波长、偏振或所产生光的时间属性。为了实现所宣布的目标，我们打算利用光子工程和理论半导体量子光学的最新发展。我们建议研究三种可能的方法，都是基于III-V半导体系统。首先，我们将用集成的量子井激子制作亚微米尺寸的柱子，以提供光子非线性，即产生量子关联所需的强光子-光子相互作用。其次，我们将利用耦合柱子之间复杂的量子干涉。第三，我们将应用一种灵活的混合方法，在这种方法中，即使在制造之后，腔也是可调的。这将使我们能够以节省时间和成本的方式探索参数空间的一大部分。实现极化激子封锁和所提出的量子井微腔系统的单光子发射肯定是一个重大突破，其影响远远超出极化电子研究的范围。基于耦合腔的方案特别有趣，因为这种现象还没有在任何物理系统中得到实验证明。在不需要单个量子发射器的情况下按需创建单光子的可能性可能导致在芯片上实现高度集成的量子光学的全新方案，而创建极化子数态可能为在半导体中实现基于玻色子量子流体的量子仿真方案铺平道路。

Single photons with tailored properties are fundamental resources in quantum optics, communication, computing, and metrology. However, creating these photon states is not entirely straightforward, and while there is a variety of methods that achieve this, they all suffer from either the complexity of the setup required or the fact that the system is hardly scalable. A practically viable implementation is thus still missing. In this proposal, we would like to address this problem by experimentally studying the system of microcavity polaritons, which are the coherent superposition of a photon confined to a short cavity, and a quantum well exciton. A flying photon is generated, when the polariton decays. A number of theoretical works have discussed the potential of polaritons for creating quantum-correlated photons, and there are already a couple of experimental demonstrations of quantum effects, such as, first-order correlations, and squeezing. The big advantage of the polariton system over schemes relying on the implementation of individual quantum emitters is its inherent scalability, robustness, and the possibility of tailoring specific properties, such as the wavelength, polarisation, or the temporal attributes of the generated light. In order to achieve the stated goals, we intend to utilise the latest developments in photonic engineering and theoretical semiconductor quantum optics. We propose to study three possible approaches, all based on III-V semiconductor systems. Firstly, we will fabricate submicrometer-sized pillars with integrated quantum well excitons to provide the photonic non-linearity, i.e., the strong photon-photon interaction required for generating the quantum correlations. Secondly, we will exploit the intricate quantum interference between coupled pillars. And third, we will apply a flexible, hybrid approach, where the cavity is tunable even after fabrication. This will allow us to explore a large segment of the parameter space in a time- and cost-efficient manner.Achieving polariton blockade and single photon emission from the proposed quantum well microcavity systems would certainly be a major breakthrough with impacts far beyond the community of polaritonic research. The scheme based on the coupled cavities is especially interesting, since that phenomenon has not experimentally been demonstrated in any physical system. The possibility to create single photons on demand without individual quantum emitters could lead to entirely novel schemes of highly integrated quantum optics on chip, and creating polariton number states could pave the way towards the implementation of quantum emulation schemes based on bosonic quantum fluids in semiconductors.