title: Spontaneous emission spectrum in double quantum dot devices
abstract: A double quantum dot device is a tunable two-level system for electronic energy states. A dc electron current was used to directly measure the rates for elastic and inelastic transitions between the two levels. For inelastic transitions, energy is exchanged with bosonic degrees of freedom in the environment. The inelastic transition rates are well described by the Einstein coefficients, relating absorption with stimulated and spontaneous emission. The most effectively coupled bosons in the specific environment of the semiconductor device used here were acoustic phonons. The experiments demonstrate the importance of vacuum fluctuations in the environment for quantum dot devices and potential design constraints for their use for preparing long-lived quantum states.
authors.affiliation: T. Fujisawa, Department of Applied Physics and DIMES, Delft University of Technology, 2600 GA Delft, Netherlands, and NTT Basic Research Laboratories, 3-1, Morinosato-Wakamiya, Atsugi, Kanagawa, 243-0198, Japan. T. H. Oosterkamp, W. G. van d.
authors.initials: T
authors.lastname: Fujisawa
authors.initials: TH
authors.lastname: Oosterkamp
authors.lastname: van der Wiel WG
authors.initials: BW
authors.lastname: Broer
authors.initials: R
authors.lastname: Aguado
authors.initials: S
authors.lastname: Tarucha
authors.initials: LP
authors.lastname: Kouwenhoven