title: Ultrafast optical spectroscopy of spectral fluctuations in a dense atomic vapor.
abstract: Transient four-wave mixing experiments with 100 fs pulses in a dense potassium vapor probe the electronic energy fluctuations that lead to optical decoherence. Echo-peak shift experiments yield a biexponential two-time correlation function of energy level fluctuations. Molecular dynamics simulations show that the slow component is a many-body excitonic contribution arising from long-range resonant interactions. The decay of the correlation function occurs on comparable time scales in theory and experiment.
authors.affiliation: JILA, University of Colorado, Boulder, CO 80309-0440, USA.
authors.forename: V O
authors.initials: VO
authors.lastname: Lorenz
authors.forename: S
authors.initials: S
authors.lastname: Mukamel
authors.forename: W
authors.initials: W
authors.lastname: Zhuang
authors.forename: S T
authors.initials: ST
authors.lastname: Cundiff