We present a detailed study of a phonon-assisted incoherent excitation mechanism of single quantum dots. A spectrally detuned continuous-wave laser couples to a quantum dot transition by mediation of acoustic phonons, whereby excitation efficiencies up to 20% with respect to strictly resonant excitation can be achieved at T=9 K. Laser-frequency-dependent analysis of the quantum dot intensity distinctly maps the underlying acoustic phonon bath and shows good agreement with our polaron master equation theory. An analytical solution for the steady-state exciton density (which is proportional to the photoluminescence) is introduced which predicts a broadband incoherent coupling process mediated by electron-phonon scattering. Moreover, we investigate the coherence properties of the emitted light with respect to strictly resonant versus phonon-assisted excitation, revealing the importance of narrow band triggered emitter-state initialization for possible applications of a quantum dot exciton system as a qubit. Publication: Phonon-assisted incoherent excitation of a quantum dot and its emission properties S. Weiler, A. Ulhaq, C. Roy, S.Hughes,S. M. Ulrich, D. Richter, M. Jetter, and P. Michler externer Link Phys. Rev. B 86, 241304(R) (2012)
Contact person: Prof. Peter Michler