Localization of light and cavity modes play an important role in optics. In photonic crystals, localization occurs at defects to the periodicity of the structure. Recently, twist in a coreless...Show moreLocalization of light and cavity modes play an important role in optics. In photonic crystals, localization occurs at defects to the periodicity of the structure. Recently, twist in a coreless photonic crystal fibre was shown to confine an optical mode. In this project, the analogous system of a rotating two-dimensional photonic crystal has been investigated. Building upon previous work by Götte, Barnett and Padgett, a wave equation for a rotating photonic crystal is derived. Although no explicit solutions have been found yet, several solving procedures are proposed. In addition, the effect of elastic deformations resulting from rotation-induced centrifugal force is investigated theoretically. We report the emergence of localized modes in a circular Bragg deformed by rotation. The wavelength of these modes is found to be proportional to the magnitude of the deformations. The localized modes reported here present a first step towards highly tunable cavity devices.Show less
This thesis gives insight into two photon quantum interference effects in quantum optics, with Hong-Ou-Mandel visibility detection. This is studied using a delay loop with different light...Show moreThis thesis gives insight into two photon quantum interference effects in quantum optics, with Hong-Ou-Mandel visibility detection. This is studied using a delay loop with different light polarizations. The single photons are created by exciting a quantum dot in a microcavity with a continuous-wave laser. We try to relate experimental results of the second order correlation function to a theoretical analysis of the obtained photon states in the system. As a result an insight into the creation of highly entangled qubit states, called cluster states, is given.Show less
In this thesis I explore the possibility of excitation with a single photon source for biomicroscopy purposes. In biomicroscopy the fluorescent properties of molecules are used to label proteins or...Show moreIn this thesis I explore the possibility of excitation with a single photon source for biomicroscopy purposes. In biomicroscopy the fluorescent properties of molecules are used to label proteins or molecules of interest. A key limitation is the effect of photobleaching: after some time all fluorescent molecules are irreversibly converted to a dark state. Photobleaching processes involve highly reactive excited states of molecules and formation of radical oxygen. Excitation with single photons represses multiphoton processes and it is therefore expected that this will reduce the photobleaching rate. So far no experiments have been done with bright cavity based single photon sources. If the cavity based single photon source at our disposal is integrated in the microscopy setup, this could be a first test system for single photon microscopy.Show less
Over the last few decades, several methods have been explored and applied to circumvent the Abbe-Rayleigh diffraction limit, probably most importantly, stochastic super-resolution fluorescence...Show moreOver the last few decades, several methods have been explored and applied to circumvent the Abbe-Rayleigh diffraction limit, probably most importantly, stochastic super-resolution fluorescence microscopy methods. Another possibility, relying only on linear classical optics, is to exploit optical superoscillations, and is far less explored to date. In this project we explore the use of optical vortices for super-resolution far-field imaging. For this, we investigate strongly focused optical fields using a number of theoretical methods, we implement an experiment where a micro-pinhole is scanned through the focus, and, explore spin-orbit interactions of strongly focused optical fields. We find that our micron-sized pinhole is able to discern structures much smaller than its own size and leads to an enhancement of the spin-orbit interaction. Our method can be implemented as a simple and fast tool for characterizing the intensity distribution of a focused field with high resolution.Show less
Cluster states are a viable resource for quantum computing where information is stored in these states and one single-qubit measurement is performed at a time. In order to generate such states, we...Show moreCluster states are a viable resource for quantum computing where information is stored in these states and one single-qubit measurement is performed at a time. In order to generate such states, we use the quanta of light - photons - as our qubits. We generate them from a quantum dot in a microcavity which serves us as a deterministic single photon source. We explore a method of generating cluster states by entangling these photons with the means of linear optical elements and post-selection. We develop a theoretical model and show that it is in an agreement with our experimental data with single photons. From this agreement, we conclude that the cluster states arise in the experimental setup and the entanglement between the photons can be confirmed to be present with further analysis using our hypothesis and possibly even the quantum state tomography in the future.Show less
This thesis is concerned with the design of numerical methods for solving the Schrödinger equation for a system of two-electrons in a double quantum dot. Theoretical background is presented for the...Show moreThis thesis is concerned with the design of numerical methods for solving the Schrödinger equation for a system of two-electrons in a double quantum dot. Theoretical background is presented for the physics of a two-electron quantum dot. Implementation of the double dot system is via the QuTiP library is discussed and a numerical approach for the treatment of the system using the density matrix formalism is presentedShow less
It has been a long term goal of physicists to control macroscopic quantum superposition states - cat states - since these connect to a number of open fundamental questions in physics: the...Show moreIt has been a long term goal of physicists to control macroscopic quantum superposition states - cat states - since these connect to a number of open fundamental questions in physics: the transition from the quantum to the classical world, the quantum measurement problem, and the area between quantum physics and theory of general relativity. Optomechanics has been identified as a method for generating cat states, however, this is yet to be achieved. The scientific community has developed increasingly improved optomechanical systems. About a decade ago, a promising optomechanical system has been demonstrated that consists of a high-stress silicon nitride membrane in the middle of a Fabry-Pérot cavity. This project concerns the development of a membrane-in-the-middle device for our lab. Our main focus lies on developing an understanding about the connection between system design and optomechanical performance. In addition, we demonstrate optomechanics for our device, and show that the initial optomechanical parameters are good. The availability of clearly defined methods for improving upon the current system parameters implies that we are moving in the right direction towards quantum optomechanical experiments.Show less
High-fidelity single photon sources are required for quantum information technologies and fundamental research. Recently near-unity single photon purity and near-unity indistinguishability have...Show moreHigh-fidelity single photon sources are required for quantum information technologies and fundamental research. Recently near-unity single photon purity and near-unity indistinguishability have been shown in resonantly pumped quantum dots embedded in an optical cavity. In this thesis we provide a theoretical framework and experimental results on polarization non-degenerate self-assembled InAs/GaAs quantum dots inside a polarization non-degenerate cavity, and show that by filtering the polarization the brightness of the single photon source can be enhanced. We furthermore describe the resulting output light analytically as a mixture of single photons and coherent light and derive a simple expression for the purity of the single photon source. Lastly we present pulsed measurements of this quantum dot-cavity system, and show that the purity of the single photon source is 98%.Show less
A cavity quantum electrodynamics system consisting of quantum dots in a micropillar cavity may form an essential building block for the creation of a quantum network. Current systems do not allow...Show moreA cavity quantum electrodynamics system consisting of quantum dots in a micropillar cavity may form an essential building block for the creation of a quantum network. Current systems do not allow for the scaling, in a simple manner, to a large network. Therefore, we introduce a scalable approach by coupling a micropillar cavity to single-mode fibers. The steps taken to achieve the fiber coupling are explained and the first tests for researching a fiber coupled cavity quantum electrodynamics system are shown. The first tests show that full input-output fiber based polarization control of a micropillar cavity at 3.5 K is possible which is important for a photon polarization based quantum network. Several experimental challenges are shown and discussed. Despite the experimental challenges, the first tests may pave the way for a more scalable approach for building a large-scale quantum network.Show less
