Lighten up: Polaritons with tunable photon-exciton coherence
(PhysOrg.com) -- Of the many exotic and counterintuitive aspects of particle and quantum physics, exciton and polariton quasiparticles are among the most interesting. An exciton forms when a photon is absorbed by a semiconductor as a Coulomb force-bound state of a (negatively-charged) electron and a (positively-charged) hole; this particle pair can be seen as an elementary excitation of condensed matter able to transport energy without the transfer of net electric charge, and moreover has size- and shape-dependent optoelectronic properties. A polariton forms due to strong coupling of a photon with an excitation of a material and among the several types of polaritons, an exciton-polariton is a composite photonic-electronic quasiparticle resulting from coupling of visible light with matter in the form of an exciton. At the same time, the difficulty of achieving increased light-matter coupling strengths has limited the development of applications operating at, for example, higher temperatures and lower...