Prof Eugene Demler (ETH Zürich)
Venue: Small Lecture Theatre
Title and abstract:
Lighting up superconductivity
Recent experiments suggest the phenomenon of light induced superconductivity above Tc in two different materials: fullerene superconductor K3C60 and high Tc cuprate YBCO. I will discuss the distinct phenomena taking place in these systems. In K3C60, the unusual character of electron-phonon interactions results in enhanced BCS pairing through optical driving and the slow relaxation of superconducting correlations after they have been created. In YBCO the light induced state is short lived and its properties can be explained from the perspective of a Floquet material. I will present a general theoretical framework for understanding Floquet materials, in which the pump-induced oscillations of a collective mode lead to the parametric generation of excitation pairs. This can result in features such as photo-induced edges in reflectivity, enhancement of reflectivity, and even light amplification.