PhD in Physics

When light illuminates nano-sized metallic structures, the free electrons in the metal collectively oscillate, creating `plasmons'. By specifically designing the geometry and arrangement of the nano-metallic structures, one can direct and concentrate light at small enough volumes, to create nanoplasmonic cavities that can enclose even single molecules. Plasmons (or light in general) have the ability to perturb the atoms of a molecule, such that vibrations are induced on its chemical bonds. These vibrations are unique and characteristic to the chemical bonds of each molecule, and usually have resonances within the mid-infrared regime. It was recently shown that one can convert these vibrational mid-infrared resonances into the higher-frequency visible regime (i.e. frequency up-conversion), where it is easier to detect and measured experimentally. However, it is not well known yet how this process emerges and how one can control it. This PhD project will focus on developing the necessary theoretical tools using cavity quantum electrodynamic (QED) descriptions, to model and understand this complex interaction between plasmons in small gaps and the vibrational behaviour of molecules. The student will also have to develop the theoretical methods to describe the up-conversion mechanism, and design new types of cavities that enhance its efficiency.