Applications of light–matter interaction in semiconductor structures

In this thesis, we study the applications of light–matter interactions in the context of quantum information processing. We consider interactions at the single- or few-photon level with semiconductor-based structures integrated within photonic setups. The work we present here, therefore, fits in well within the wider field of optical quantum information processing and technologies, whereby photons are utilised in the encoding, manipulation and transmission of information, as well as solid-state quantum optics, where the spin plays the role of the qubit. The work we present here is highly theoretical and we, therefore, keep in mind experimental challenges. We first present the mathematical foundations of quantum mechanics, then move on to describe key concepts and formulations from the theory of quantum optics that we will use in our work. We describe in detail the important quantum feature of entanglement, which serves as a resource in various quantum technologies. This motivates us to study the generation of entanglement between spectrally dissimilar solid-state emitters using readily accessible optical states. The method we propose builds up the generated entanglement in a cumulative manner and is heralded by the detection of photons. We also study the effects of different sources of loss on the implementation of the scheme. Next, we consider the use of the spin–photon interface to perform quantum error correction; specifically, syndrome extraction in quantum surface codes. Making use of quantum dots within micropillar cavities, we show how a photonic implementation of the surface code can make use of the resulting light–matter interaction in order to detect the presence of errors. We show that the scheme is robust to errors in the frequency detuning by using the confidence as a figure of merit. We also study the generation of entanglement between spectrally dissimilar spin systems and consider the efficiency and fidelity of such a scheme. Finally, we study the light–matter interaction within a semiconductor-based device intended as a component within a wider quantum optical network. Using the input–output formalism, we obtain the single- and two-photon scattering matrices that allow us to describe the transport properties of the proposed setup. We also discuss the presence of the non-linearity in the interaction and the photon statistics of the transmitted field for a weak coherent state as the input.