title: Coherent population trapping with controlled interparticle interactions.
abstract: We investigate coherent population trapping in a strongly interacting ultracold Rydberg gas. Despite the strong van der Waals interactions and interparticle correlations, we observe the persistence of a resonance with subnatural linewidth at the single-particle resonance frequency as we tune the interaction strength. This narrow resonance cannot be understood within a mean-field description of the strong Rydberg-Rydberg interactions. Instead, a many-body density matrix approach, accounting for the dynamics of interparticle correlations, is shown to reproduce the observed spectral features.
authors.affiliation: Physikalisches Institut, Universität Heidelberg, Philosophenweg 12, 69120 Heidelberg, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Schempp
authors.forename: G
authors.initials: G
authors.lastname: Günter
authors.forename: C S
authors.initials: CS
authors.lastname: Hofmann
authors.forename: C
authors.initials: C
authors.lastname: Giese
authors.forename: S D
authors.initials: SD
authors.lastname: Saliba
authors.forename: B D
authors.initials: BD
authors.lastname: Depaola
authors.forename: T
authors.initials: T
authors.lastname: Amthor
authors.forename: M
authors.initials: M
authors.lastname: Weidemüller
authors.forename: S
authors.initials: S
authors.lastname: Sevinçli
authors.forename: T
authors.initials: T
authors.lastname: Pohl