LMI Seminar: Ultrastrong and deep strong light-matter coupling with nanoparticle supercrystals
Stephanie Reich, Freie University Berlin
In my talk, I will present supercrystals made of plasmonic gold nanoparticles. They are materials with exceptionally strong interaction with light. They may also be used to place molecules in an extreme electromagnetic environment.
Most materials interact only weakly with light, which is why we can treat light as an external perturbation. There has been growing interest in systems where light-matter interaction is much stronger so that the interaction energy becomes comparable to other characteristic energies of the system. In the regime of deep strong coupling the Rabi frequency exceeds the bare excitation energy of a material. This regime leads to exotic effects like the population of the ground state with virtual photons, phase transitions, and a breakdown of the Purcell effect. Here I show that densely packed supercrystals made of gold nanoparticles naturally are in the regime of deep strong coupling. I will present measurements of their plasmon-polaritons and confirm the breakdown of the Purcell effect. If time permits, I will discuss a universal model to treat light-matter coupling in systems of different dimension and the strongest light-matter coupling we can reasonably expect to achieve.