  We study phonon emission in a GaAs/AlGaAs double quantum dot by monitoring
the tunneling of a single electron between the two dots. We prepare the system
such that a known amount of energy is emitted in the transition process. The
energy is converted into lattice vibrations and the resulting tunneling rate
depends strongly on the phonon scattering and its effective phonon spectral
density. We are able to fit the measured transition rates and see imprints of
interference of phonons with themselves causing oscillations in the transition
rates.
