Speaker: 
Johannes Feist - Universidad Autónoma de Madrid

Title: 
Molecular polaritonics from the macroscopic to the single-molecule regime

Abstract:
When the interaction of molecular excitations with confined light modes is sufficiently strong, the strong light-matter coupling regime is entered and the eigenstates of the system become hybrid light-matter states called polaritons. In wavelength-scale optical cavities, polaritons are delocalized states that arise due to the collective interaction of macroscopic numbers of molecules with the same light mode and thus have fundamentally different characteristics than the single-molecule excitations that they are formed from. Polariton formation thus provides a control knob that can be used to affect a number of material properties without having to modify the material itself. I will discuss several examples of such effects, including changes of the absorption and emission characteristics of a material, of energy transfer between molecular species, and even of photochemical reactions. I will then discuss situations in which plasmonic nanocavities are used to confine light to strongly subwavelength dimensions, increasing the light-matter interaction sufficiently that the strong-coupling regime can be reached with just one or a few molecules. In these cases, the energy level structure and dynamics of the molecule are affected even more strongly than in the collective case. Additionally, ultrafast losses are unavoidable in such cavities, leading to additional loss-induced effects. I will discuss several strategies to not only mitigate but exploit these fast losses.

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QuCoLiMa Talks are the weekly seminar of the collaborative research center TRR 306 QuCoLiMa (Quantum Cooperativity of Light and Matter). The talks are given by (external) experts, whose research falls within the scope of QuCoLiMa.

More information at www.qucolima.de/talks