Physics & Astronomy Colloquium
Dr. Thomas G. Folland Postdoctoral Scholar Vanderbilt University
“Infrared Polaritonics: Coupling Long Wavelength Light to Quantum Systems”
Abstract: Generating, manipulating and detecting quantum states of light is a key challenge for realizing practical quantum technology. Whilst microwaves and visible/near-infrared light have been widely used for such efforts, the mid-infrared to terahertz region of the electromagnetic spectrum (λ=3-300µm) could offer a host of advantages. Optically active transitions in the infrared (including phonons and intraband states) often have relatively strong dipole moments and optical non-linearities, and can be controlled through multiple techniques. However, the current generation of infrared technology is generally insufficient to fully exploit quantum coherent phenomena. To achieve strong coherent interactions between long wavelength light and nano- to meso-scale quantum systems, we can turn to surface polaritons. These quasiparticles occur when light couples to coherently oscillating charges in a material, commonly electrons or polar phonons, forming tightly confined evanescent waves. In this colloquium I will I will discuss recent work on polaritons in 2D materials including graphene, hexagonal boron nitride, and molybdenum trioxide. The highly anisotropic crystal structure of these materials imparts important consequences for their optical and polaritonic properties. By integrating these 2D materials with different devices and systems we can create emergent phenomena such as nanoscale light waveguiding, not possible using conventional optics. Furthermore, I will show how semiconducting materials can support coherent coupling between propagating surface polaritons and an absorbing state. This suggests a route to realizing new types of detectors, light sources, and ultimately entangled systems which could form the basis of the next generation of infrared technology.