Design and Simulations of Quantum Light Sources

The subject of this thesis is quantum dot based single-photon sources (SPSs) with potential applications in quantum computing and quantum communication. The thesis
is theoretical, and we have designed, optimized, and performed optical simulations of various quantum dot based SPSs, all featuring rotational symmetry. For this purpose,
we made use of the Fourier modal method with open boundary conditions combined with a standard scattering matrix formalism. This method allows for in-depth physical insight. The main focus has been on the collection efficiency with a minor focus on the indistinguishability, two important SPS figures of merit. We demonstrate that the trade-off between collection efficiency and indistinguishability, within the standard cavity quantum electrodynamics design scheme, can be circumvented by combining the dielectric screening effect with Purcell enhancement using the hourglass SPS design. We elucidate the physical origin of the breakdown of the single-mode Fabry-Pérot model for the nanopost SPS design. The fundamental HE11 mode significantly scatters into radiation modes causing this breakdown. Surprisingly, this scattering mechanism significantly benefits the collection efficiency as the scattered radiation field constructively interferes with the direct transmission of the fundamental HE11 mode in the far field. Additionally, this effect also decouples the collection efficiency from the Purcell factor and the nanopost features broadband collection efficiency with the maximum values being off-resonance. We hope that this work can inspire unconventional SPS design strategies. Lastly, we demonstrate how a circular Bragg grating surrounding a dielectric wire can increase the β factor towards unity due to suppression of the background emission caused by a photonic band gap effect. This simulation and analysis was done using a novel and efficient analytical method. We then applied this result to the photonic nanowire SPS design and demonstrated how the collection efficiency could be further increased. Additionally, we also show the beneficial effects of adding a circular Bragg grating around the micropillar SPS.