Topological polariton states in photonic lattices

半导体纳米技术的最新进展导致了新一代坚固的可控结构，在这种结构中，光和物质之间的耦合可以在亚微米尺度上进行操作。在这些结构中，可以产生光和物质(激子)的混合物--新的准粒子--极化子。极化子的有效质量非常小，因此在高温下可能会凝聚成单一的量子态。这种宏观占据态具有类似于原子玻色-爱因斯坦凝聚态的性质。此外，虽然在自由空间中传播的光子不会相互作用，但极化波函数中的物质分量可以实现强烈的粒子间相互作用。这种非线性导致了丰富的现象，从光的超流、超低功率的自局域波包(孤子)到单光子和纠缠光子对的产生。本项目涉及耦合零维微谐振器晶格中极化子的研究，其中晶格周期势、自旋和轨道自由度之间的耦合以及外加磁场的综合效应允许使用极化子准粒子(零电荷玻色子)来研究凝聚态物理中的拓扑效应。这个项目的重点将放在研究这些晶格边界上的拓扑保护的边态，以及增益、损耗和非线性对极化子拓扑的影响。

Recent advances in semiconductor nano-technology have led to a new generation of robust controllable structures where manipulation of coupling between light and matter can be performed on a sub-micrometer scale. In these structures novel quasiparticles - polaritons - which are a mixture of light and matter (excitons) can be created. Polaritons have a very small effective mass, and thus may condense in a single quantum state at high temperatures. This macroscopically occupied state has properties similar to those of atomic Bose-Einstein condensates. In addition, while photons propagating in free space do not interact, the matter component in the polariton wavefunction enables strong inter-particle interactions. This nonlinearity gives rise to rich phenomena ranging from superfluidity of light, ultra-low power self-localised wavepackets (solitons) to generation of single photons and entangled photon pairs. This project concerns the investigation of polaritons in lattices of coupled zero-dimensional microresonators, where the combined effects of the lattice periodic potential, the coupling between spin and orbital degrees of freedom and applied magnetic field allow topological effects from condensed matter physics to be studied using polariton quasiparticles (bosons of zero charge). A particular emphasis on this project will be placed on the study of topologically protected edge states at the boundaries of these lattices, and the effects of gain, loss and nonlinearity on the polariton topology.