Quantum Theory and Technology

The Quantum Theory and Technology (QTT) group at the University of Southampton focuses on theoretical research in the fields of cavity quantum electrodynamics (CQED) and mid-infrared nanophotonics.  

We are world-leading in the investigation of the ultimate limits of light-matter coupling at the nanoscale, including the strong and ultra strong light-matter coupling regimes.  

We demonstrated, both theoretically and in collaboration with our experimental colleagues, how the light-matter coupling in nanophotonic resonators can be used to modify material properties, and even to create novel artificial atoms in which two electrons are held together by a trapped photon, making photonics a tool of quantum material engineering. We also explore applications of CQED to high-energy physics, with one of our recent proposals demonstrating how CQED effects can be used to measure the density of dense Positronium gases. 

One important branch of our investigations regards phonon polaritons, excitations in which oscillations of the electromagnetic field and of the crystal lattice hybridise, leading to novel optoelectronic functionalities which can find applications in nanodevices for sensing and quantum technology applications. 

More generally, the mid-infrared spectral range in which most of our research finds application, is significant because this spectral range has applications in various fields, including environmental sensing, medical diagnostics, and security. By exploring and exploiting the properties of light in the mid-infrared region, the QTT group's research can contribute to the development of high-performance photonic devices and systems for practical applications in these domains.