Room-temperature quantum fluids of light

Light-matter interaction is at the heart of most optical processes we are familiar with such as absorption, emission and scattering. These are normally treated by assuming that light does not significantly modify the underlying electronic states of the material it interacts with. The extreme case where light-matter interaction is so strong that it must be treated non-pertubatively has been termed the strong-coupling regime. In this regime, new half-light, half-matter quasiparticles called polaritons emerge. We will describe some of the fascinating new physics that occur in this regime such as how polaritons can be used to create room-temperature analogs to Bose-Einstein condensates and superfluid He using light instead of atoms. We will also discuss some of the unique applications that emerge when organic molecules are used as the active medium, such as using strong light-matter coupling to increase the brightness of inefficient molecular emitters, engineer the response of solar cells and photodetectors and modify photochemistry.

Stéphane Kéna-Cohen is an Assistant Professor of Engineering Physics at Polytechnique Montréal and the Canadian Research Chair in Hybrid and Molecular Photonics. He received his BEng from McGill (2004) and PhD from Princeton University (2010), both in Electrical Engineering. He then moved to the Physics Department at Imperial College London, where he spent 4 years as a post-doctoral researcher and Junior Research Fellow. His background as an engineer and physicist is reflected in the work he does. Part of his group works on the development of optoelectronic devices based on organic and hybrid semiconductors. He collaborates with several multinational companies in the area and holds 2 patents related to organic electronics. At the same time, he devotes important efforts towards studying exotic quantum effects in molecular systems and gaining a deep understanding of the inner workings of new materials.