Quantum-dot single photon source performance with quasi-coherent excited state preparation schemes

The preparation of quantum-dot qubits in the excited state is an integral part of the performance of an on-demand single photon source. Recent excitation schemes strategically use pulses that avoid spectral overlap with the qubit emission for easier differentiation between the pump and signal. In this work, we look at the robustness of two such pumping schemes, (i) a dichromatic pulse, and (ii) a notch-filtered adiabatic rapid passage (NARP) approach, in the presence of phonon coupling. We find that due to large instantaneous pulse strengths, the dichromatic pulse suffers from phonon-induced pure dephasing and can have up to 50% worse performance as a single photon source. On the other hand, the NARP approach is more robust against the phonon coupling due to a weaker and smoother pulse profile.