title: Phonon-assisted population inversion of a single InGaAs/GaAs quantum dot by pulsed laser excitation.
abstract: We demonstrate a new method to realize the population inversion of a single InGaAs/GaAs quantum dot excited by a laser pulse tuned within the neutral exciton phonon sideband. In contrast to the conventional method of inverting a two-level system by performing coherent Rabi oscillation, the inversion is achieved by rapid thermalization of the optically dressed states via incoherent phonon-assisted relaxation. A maximum exciton population of 0.67±0.06 is measured for a laser tuned 0.83 meV to higher energy. Furthermore, the phonon sideband is mapped using a two-color pump-probe technique, with its spectral form and magnitude in very good agreement with the result of path-integral calculations.
authors.affiliation: Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, United Kingdom.
authors.forename: J H
authors.initials: JH
authors.lastname: Quilter
authors.affiliation: Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, United Kingdom.
authors.forename: A J
authors.initials: AJ
authors.lastname: Brash
authors.affiliation: Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, United Kingdom.
authors.forename: F
authors.initials: F
authors.lastname: Liu
authors.affiliation: Institut für Theoretische Physik III, Universität Bayreuth, 95440 Bayreuth, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Glässl
authors.affiliation: Institut für Theoretische Physik III, Universität Bayreuth, 95440 Bayreuth, Germany.
authors.forename: A M
authors.initials: AM
authors.lastname: Barth
authors.affiliation: Institut für Theoretische Physik III, Universität Bayreuth, 95440 Bayreuth, Germany.
authors.forename: V M
authors.initials: VM
authors.lastname: Axt
authors.affiliation: Hitachi Cambridge Laboratory, Hitachi Europe Ltd., Cambridge CB3 0HE, United Kingdom.
authors.forename: A J
authors.initials: AJ
authors.lastname: Ramsay
authors.affiliation: Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, United Kingdom.
authors.forename: M S
authors.initials: MS
authors.lastname: Skolnick
authors.affiliation: Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, United Kingdom.
authors.forename: A M
authors.initials: AM
authors.lastname: Fox