title: Quantum light from a whispering-gallery-mode disk resonator.
abstract: Optical parametric down-conversion has proven to be a valuable source of nonclassical light. The process is inherently able to produce twin-beam correlations along with individual intensity squeezing of either parametric beam, when pumped far above threshold. Here, we present for the first time the direct observation of intensity squeezing of -1.2  dB of each of the individual parametric beams in parametric down-conversion by use of a high quality whispering-gallery-mode disk resonator. In addition, we observed twin-beam quantum correlations of -2.7  dB with this cavity. Such resonators feature strong optical confinement and offer tunable coupling to an external optical field. This work exemplifies the potential of crystalline whispering-gallery-mode resonators for the generation of quantum light. The simplicity of this device makes the application of quantum light in various fields highly feasible.
authors.affiliation: Max Planck Institute for the Science of Light, Erlangen, Germany.
authors.forename: J U
authors.initials: JU
authors.lastname: Fürst
authors.forename: D V
authors.initials: DV
authors.lastname: Strekalov
authors.forename: D
authors.initials: D
authors.lastname: Elser
authors.forename: A
authors.initials: A
authors.lastname: Aiello
authors.forename: U L
authors.initials: UL
authors.lastname: Andersen
authors.forename: Ch
authors.initials: Ch
authors.lastname: Marquardt
authors.forename: G
authors.initials: G
authors.lastname: Leuchs