title: Stimulated and spontaneous optical generation of electron spin coherence in charged GaAs quantum dots.
abstract: We report on the coherent optical excitation of electron spin polarization in the ground state of charged GaAs quantum dots via an intermediate charged exciton (trion) state. Coherent optical fields are used for the creation and detection of the Raman spin coherence between the spin ground states of the charged quantum dot. The measured spin decoherence time, which is likely limited by the nature of the spin ensemble, approaches 10 ns at zero field. We also show that the Raman spin coherence in the quantum beats is caused not only by the usual stimulated Raman interaction but also by simultaneous spontaneous radiative decay of either excited trion state to a coherent combination of the two spin states.
authors.affiliation: The H. M. Randall Laboratory of Physics, The University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: M V Gurudev
authors.initials: MV
authors.lastname: Dutt
authors.forename: Jun
authors.initials: J
authors.lastname: Cheng
authors.forename: Bo
authors.initials: B
authors.lastname: Li
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Xu
authors.forename: Xiaoqin
authors.initials: X
authors.lastname: Li
authors.forename: P R
authors.initials: PR
authors.lastname: Berman
authors.forename: D G
authors.initials: DG
authors.lastname: Steel
authors.forename: A S
authors.initials: AS
authors.lastname: Bracker
authors.forename: D
authors.initials: D
authors.lastname: Gammon
authors.forename: Sophia E
authors.initials: SE
authors.lastname: Economou
authors.forename: Ren-Bao
authors.initials: RB
authors.lastname: Liu
authors.forename: L J
authors.initials: LJ
authors.lastname: Sham