Collective Dipolar Behaviour in Atomic Gases - Superradiance, Subradiance, and Hyperradiance

Robert Bettle
April 5th, 2018 ROBERT BETTLES Durham University

The interaction between light and an ensemble of scatterers can be significantly modified if the scatterers interact strongly with each other. For example, dipole-dipole interactions in ensembles of atoms, ions, plasmonic nanostructures, etc., can produce striking collective phenomena including modified decay rates (superradiance and subradiance), lineshifts, Fano resonances, and near-perfect optical reflection. A common interpretation of this collective behaviour involves considering the collective eigenmodes of the system, the eigenvalues of which determine the decay and resonance properties. However, I will present results from a recent experiment and numerical simulations which challenge this simple eigenmode picture of scattering. After initial pulsed excitation of a dense cloud of atoms, the ensuing fluorescent flash decays faster than the eigenmodes would predict (‘hyperradiance’), whilst (contrary to the typical linewidth—decay-rate correspondence) the linewidth experiences effectively no broadening.

Seminar, April 5, 2018, 12:00. ICFO’s Seminar Room

Hosted by Prof. Darrick Chang