title: Superradiant Emission from a Collective Excitation in a Semiconductor.
abstract: We report an anomalous wide broadening of the emission spectra of an electronic excitation confined in a two-dimensional potential. We attribute these results to an extremely fast radiative decay rate associated with superradiant emission from the ensemble of confined electrons. Lifetimes extracted from the spectra are below 100 fs and, thus, 6 orders of magnitude faster than for single particle transitions at similar wavelength. Moreover, the spontaneous emission rate increases with the electronic density, as expected for superradiant emission. The data, all taken at 300 K, are in excellent agreement with our theoretical model, which takes into account dipole-dipole Coulomb interaction between electronic excitations. Our experimental results demonstrate that the interaction with infrared light, which is usually considered a weak perturbation, can be a very efficient relaxation mechanism for collective electronic excitations in solids.
authors.affiliation: Université Paris Diderot, Sorbonne Paris Cité, Laboratoire Matériaux et Phénomènes Quantiques, UMR7162, 75013 Paris, France.
authors.forename: T
authors.initials: T
authors.lastname: Laurent
authors.affiliation: Université Paris Diderot, Sorbonne Paris Cité, Laboratoire Matériaux et Phénomènes Quantiques, UMR7162, 75013 Paris, France.
authors.forename: Y
authors.initials: Y
authors.lastname: Todorov
authors.affiliation: Université Paris Diderot, Sorbonne Paris Cité, Laboratoire Matériaux et Phénomènes Quantiques, UMR7162, 75013 Paris, France.
authors.forename: A
authors.initials: A
authors.lastname: Vasanelli
authors.affiliation: Université Paris Diderot, Sorbonne Paris Cité, Laboratoire Matériaux et Phénomènes Quantiques, UMR7162, 75013 Paris, France.
authors.forename: A
authors.initials: A
authors.lastname: Delteil
authors.affiliation: Université Paris Diderot, Sorbonne Paris Cité, Laboratoire Matériaux et Phénomènes Quantiques, UMR7162, 75013 Paris, France.
authors.forename: C
authors.initials: C
authors.lastname: Sirtori
authors.affiliation: Laboratoire de Photonique et Nanostructures, CNRS, 91460 Marcoussis, France.
authors.forename: I
authors.initials: I
authors.lastname: Sagnes
authors.affiliation: Laboratoire de Photonique et Nanostructures, CNRS, 91460 Marcoussis, France.
authors.forename: G
authors.initials: G
authors.lastname: Beaudoin