Exciton-Polariton Trapping and Potential Landscape Engineering

Exciton-polaritons in semiconductor microcavities have advanced to become a model system for studying dynamical Bose-Einstein condensation, macroscopic coherence, many-body effects, nonclassical states of light and matter, and possibly quantum phase transitions in a solid state. Being low mass bosons, these light-matter quasiparticles can condense at comparably high temperatures up to 300K, while preserving fundamental properties such as coherence in space and time domain even when they are out of equilibrium with the environment. Although the presence of an in-plane polariton confinement potential is not strictly necessary in order to observe condensation of polaritons, engineering the polariton confinement is a key to controlling, shaping and directing the flow of polaritons. Prototype polariton-based optoelectronic devices rely on ultrafast photon-like velocities and strong nonlinearities, as well as on tailored confinement. Nanotechnology provides several pathways to achieving such a confinement, and the specific features and advantages of the different techniques are discussed in this paper. As hybrid exciton-photon quasiparticles, polaritons can be trapped via their excitonic as well as their photonic component, which leads to a wide choice of highly complementary techniques. Here we highlight the almost free choice of trapping geometries and depths of confinement that provides a powerful tool for control and manipulation of polariton systems both in semi-classical and quantum domain. Furthermore, the possibility to observe effects of polariton blockade, Mott insulator physics, and population of higher-order bands in sophisticated lattice potentials is discussed. The observation of such effects will signify the opportunity for the realization of novel polaritonic non-classical light sources and quantum simulators.