Physics of periodic and quasi-periodic polariton systems

• Applicants: Dr. Xuekai Ma; Professor Dr. Stefan Schumacher
• Subject Area: Theoretical Condensed Matter Physics
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 519608013

Light-matter interaction has attracted a great deal of attention in modern physics and material sciences. Many unique and unconventional properties have been reported on the journey to the efficient control of light (or photons). A light-matter coupled state of particular current interest is the exciton-polariton, a quasiparticle composed of a photon and an exciton. Polaritons in planar semiconductor microcavities have been intensively studied over the past decade. Microcavity polaritons were demonstrated to have potential applications in all-optical circuits, low-threshold lasers, information processing, and light propagation control. In the proposed project, we will investigate the nonlinear dynamics of polaritons in periodic and quasi-periodic lattices with an emphasis on the following three aspects. Firstly, 1D lattices and superlattices will be used to trap polaritons. In this case, localization and oscillatory dynamics of polaritons will be studied, including the influence of different nonlinearities. Secondly, in the 2D case, richer lattice structures can be realized with more complex photonic band structures leading to intriguing behavior of polaritons. Especially, in the presence of spin-orbit coupling and disorder, new properties are expected to be observed such as Anderson localization, antichiral modes, and topological insulators. Thirdly, moiré lattices, that are currently being investigated in a large number of physical systems, will be explored here in the non-equilibrium highly nonlinear polariton systems. We will theoretically design polaritonic moiré-type lattices to bring new concepts to this system and develop novel potential applications of polaritonic devices. Simultaneously, singular features in polaritonic moiré lattices will lead to a broad interest and attract attention from other physical disciplines. The project includes an interdisciplinary mix of many-body physics, condensation phenomena, non-equilibrium physics, and nonlinear optics. With the complex interplay between nonlinearity, spin-orbit coupling, and many-body physics in the non-equilibrium (quasi-)periodic polariton systems the results of our project will significantly extend the scope of nonlinear polariton physics, with potential new applications of polaritons in functional polaritonic device concepts.

• DFG Programme: Research Grants