We introduce an intuitive and semi-analytical polaron master equation approach to model pulsedriven population inversion and emitted single photons from a quantum dot exciton. The master equation theory allows one to identify important phonon-induced scattering rates analytically, and fully includes the role of the time-dependent pump field. As an application of the theory, we first study a quantum dot driven by a time-varying laser pulse on and off resonance, showing the population inversion caused by acoustic phonon emission in direct agreement with recent experiment of Quilter et al., Phys Rev Lett 114, 137401 (2015). We then model quantum dots in weakly coupled cavities and show the difference in population response between exciton-driven and cavity-driven systems. Finally, we assess the nonresonant phonon-assisted loading scheme with a quantum dot resonantly coupled to a cavity as a deterministic single photon source, and compare and contrast the important figures of merit with direct Rabi oscillation of the population using a resonant π pulse, where the latter is shown to be much more efficient.

We present an open-system master equation study of the coherent and incoherent resonance fluorescence spectrum from a two-level quantum system under coherent pulsed excitation. Several pronounced features which differ from the fluorescence under a constant drive are highlighted, including a multi-peak structure and a pronounced off-resonant spectral asymmetry, in stark contrast to the conventional symmetrical Mollow triplet. We also study semiconductor quantum dot systems using a polaron master equation, and show how the key features of dynamic resonance fluorescence change with electron-acoustic-phonon coupling.The theory of resonant scattering of light from a twolevel system (TLS) is a major achievement in quantum optics and provides an experimentally accessible gateway to probing strong-field quantum optics. In recent decades, advances in the ability to coherently manipulate atomic systems with light has allowed for a breadth of technological innovations which harness the quantum mechanical properties of these systems [1]. Furthermore, quantum dots (QDs) -semiconductor materials confined in three dimensions, with excited electron-hole pairs (excitons) mimicking the behaviour of an excited atom, can serve as "artificial atoms", maintaining the physics of the quantized system's interaction with the electromagnetic field, but with tunable properties and potential for scalability [2]. Semiconductor QDs have been the subject of much recent research for their potential as sources of quantum light, particularly single and entangled photons [3]. While constant excitation with a continuous wave (cw) laser drive can be used to create a TLS singlephoton source, often technological proposals require a deterministic source -one that can be triggered on-demand. This is typically done by an optical pulse, which renders resonance fluorescence (RF) of a TLS a genuine timedependent quantum dynamical process.The usual features of the RF spectrum under strong cw excitation manifest as the so-called Mollow triplet [4], where the power spectrum of the scattered field takes on a characteristic three-peak resonance structure due to radiative transitions between eigenstates of the system Hamiltonian, as well as a delta function peak at the (monochromatic) drive frequency corresponding to coherent elastic scattering. However, under excitation by a short pulse, the RF spectrum can take on features which obscure or eliminate this characteristic spectrum, especially under off-resonant excitation. The pulsed RF spectrum has been studied theoretically in atomic systems [5][6][7][8][9][10], and more recently in QD-cavity systems for on-resonance excitation [11], where a dynamic spectrum has been observed in the presence of cavity coupling [12].In this Letter, we describe the unique features of pulsed * c.gustin@queensu.ca RF spectra in depth using a master equation approach, and explore the different effects under time-dependent excitation, which are of interest to emerging experimental studies of pulsed quantum optical systems. In particul...

Using a polaron master equation approach we investigate the resonance fluorescence spectra from coherently driven quantum dots (QDs) coupled to an acoustic phonon bath and a photonic crystal waveguide with a rich local density of photon states (LDOS). Resonance fluorescence spectra from QDs in semiconductor crystals are known to show strong signatures of electron-phonon interactions, but when coupled to a structured photonic reservoir, the QD emission properties are also determined by the frequency dependence of the LDOS of the photon reservoir. Here, we investigate the simultaneous role of coupled photon and phonon baths on the characteristic Mollow triplet spectra from a strongly driven QD. As an example structured photonic reservoir, we first study a photonic crystal coupled cavity waveguide, and find that photons and phonons have counter-interacting effects near the upper mode-edge of the coupled-cavity waveguide, thus establishing the importance of their separate roles in determining the emission spectra. The general theory is developed for arbitrary photonic reservoirs and is further applied to determine resonance the fluorescence spectra from a realistic, disordered W1 photonic crystal waveguide showing important photon-phonon interaction effects that are directly relevant to emerging experiments and theoretical proposals.