title: Voltage-controlled optics of a quantum dot.
abstract: We show how the optical properties of a single semiconductor quantum dot can be controlled with a small dc voltage applied to a gate electrode. We find that the transmission spectrum of the neutral exciton exhibits two narrow lines with approximately 2 mueV linewidth. The splitting into two linearly polarized components arises through an exchange interaction within the exciton. The exchange interaction can be turned off by choosing a gate voltage where the dot is occupied with an additional electron. Saturation spectroscopy demonstrates that the neutral exciton behaves as a two-level system. Our experiments show that the remaining problem for manipulating excitonic quantum states in this system is spectral fluctuation on a mueV energy scale.
authors.affiliation: Center for NanoScience, Department für Physik, Ludwig-Maximilians-Universität, Geschwister-Scholl-Platz 1, 80539 Munich, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Högele
authors.forename: Stefan
authors.initials: S
authors.lastname: Seidl
authors.forename: Martin
authors.initials: M
authors.lastname: Kroner
authors.forename: Khaled
authors.initials: K
authors.lastname: Karrai
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Warburton
authors.forename: Brian D
authors.initials: BD
authors.lastname: Gerardot
authors.forename: Pierre M
authors.initials: PM
authors.lastname: Petroff