title: Voltage control of the spin dynamics of an exciton in a semiconductor quantum dot.
abstract: We report the observation of a spin-flip process in a quantum dot whereby a dark exciton with total angular momentum L = 2 becomes a bright exciton with L = 1. The spin-flip process is revealed in the decay dynamics following nongeminate excitation. We are able to control the spin-flip rate by more than an order of magnitude simply with a dc voltage. The spin-flip mechanism involves a spin exchange with the Fermi sea in the back contact of our device and corresponds to the high temperature Kondo regime. We use the Anderson Hamiltonian to calculate a spin-flip rate, and we find excellent agreement with the experimental results.
authors.affiliation: School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, UK.
authors.forename: J M
authors.initials: JM
authors.lastname: Smith
authors.forename: P A
authors.initials: PA
authors.lastname: Dalgarno
authors.forename: R J
authors.initials: RJ
authors.lastname: Warburton
authors.forename: A O
authors.initials: AO
authors.lastname: Govorov
authors.forename: K
authors.initials: K
authors.lastname: Karrai
authors.forename: B D
authors.initials: BD
authors.lastname: Gerardot
authors.forename: P M
authors.initials: PM
authors.lastname: Petroff