Molecular Photonics in the Strong Coupling Regime

光与物质的相互作用是我们所熟悉的吸收、发射和散射等大多数光学现象的核心。我们通常通过假设光不会显著改变与之相互作用的材料的底层电子状态来处理这些问题。光与物质的相互作用是如此之强，以至于这种假设失效的极端情况被创造为强耦合状态。在这种状态下，新的半光半物质准粒子出现，称为极化子。在有机半导体薄膜中——显示技术和低成本太阳能电池中使用的同一类材料——极化子在室温下很容易形成。本计划将研究强耦合状态下的集体量子现象。它将关注两种不同的制度，其中发生了迷人的物理学。首先，在高密度下，极化子可以形成一种称为玻色-爱因斯坦凝聚的宏观量子态。我们将设计一种基于开壳分子的新型极化子凝聚体，使磁光效应得以出现。此外，我们将使用极化子凝聚体的晶格来模拟一种称为多体局域化的复杂现象。这将使我们进一步了解量子物理学和经典物理学之间的障碍。其次，在低密度下，强光-物质耦合的出现可以改变有机分子内部或分子之间发生的分子过程。这些过程可以改变的程度很大程度上取决于系统中每个光学模式的分子数量。我们将研究与提高有机发光二极管效率直接相关的两个过程的修改：反向系统间交叉和三重态-三重态湮灭。通过设计纳米级光学腔，我们将达到一个可以显着提高这些过程速率的制度。该项目的研究结果将直接应用于传感、光电子学和我们模拟复杂量子系统的能力。完成后，该计划将培养3名博士，2名硕士和5名本科学生，他们在光子学，半导体科学，量子技术和纳米制造方面具有广泛的技能，这是支持加拿大技术产业优先领域所急需的。

Light-matter interaction is at the heart of most optical phenomena that we are familiar with such as absorption, emission and scattering. We normally treat these by assuming that light does not significantly modify the underlying electronic states of the material it interacts with. The extreme case where light-matter interaction is so strong that this assumption fails has been coined the strong coupling regime. In this regime, new half-light, half-matter quasiparticles called polaritons emerge. In thin films of organic semiconductors--the same class of materials used in display technologies and low-cost solar cells--polaritons can readily form at room temperature. This Program will study collective quantum phenomena in the strong-coupling regime. It will focus on two distinct regimes, where fascinating physics occur. First, at high densities, polaritons can form a macroscopic quantum state termed a Bose-Einstein condensate. We will engineer a novel type of polariton condensate, based on open-shell molecules that will allow for magneto-optical effects to emerge. In addition, we will use lattices of polariton condensates to simulate a complex phenomenon known as many-body localization. This will allow us to gain further understanding of the barrier between quantum and classical physics. Second, at low densities, the emergence of strong light-matter coupling can modify molecular processes that occur within or between organic molecules. The extent to which these processes can be modified depends strongly on the number of molecules per optical mode in the system. We will investigate modifications of two processes directly relevant to increasing the efficiency of organic light-emitting diodes: reverse intersystem crossing and triplet-triplet annihilation. By engineering nanoscale optical cavities, we will reach a regime where the rates for these processes can be significantly enhanced. The findings from this Program will have direct applications in sensing, optoelectronics and our ability to simulate complex quantum systems. At completion, the Program will have trained 3 PhD, 2 MSc and 5 undergraduate students with a broad skill set in photonics, semiconductor science, quantum technologies and nanofabrication highly needed to support priority areas in Canada's technology industry.