Classical computer have difficulties simulating specific complex problems, therefore other computation options are being explored. One of these options is the quantum computer, which is expected to excel in various industries. The challenge for the quantum computer is scaling it up to a high number of qubits. The diamond-based quantum computer is a suitable candidate for quantum computer, because it can be made scalable, with long coherence times, relatively high temperatures and low cross talk. Making such a scalable modular quantum computer using diamond qubits requires heterogeneous integration of optical components. Multiple integrations techniques for optical components exist, however in this thesis we are particularly interested in integrating a superconducting nanowire single photon detector (SNSPD) with pick & place onto the quantum chip to read out the photons emitted by diamond color-centers. The main goal of this thesis is to find out which integration scheme leads to the highest on-chip detection efficiency of a pick & place on waveguide integrated SNSPD.

In this work we designed a silicon nitride structure with low loss tapered support structures. Next different releasing methods are introduced to release the fabricated silicon nitride structure independent of the material stack and with a high yield. Lastly, we show how waveguide structures can be pick & placed on receptor chips that underwent surface treatment.

Demand for high density, high bandwidth, and low power Integrated Circuits (ICs) is rapidly increasing even as Moore's Law is starting to plateau. Among the new wave of technologies that are meant to continue the prevalent trend of semiconductor device scaling, 3D System Integration promises many advantages over traditional single-planar designs. This technology enables designers to stack multiple dies and unlock new functionality by reducing the footprint of the final device package. Using 3D Integration, multiple different types of chiplets (Digital IC, Analog IC, MEMS) can be integrated into a single package, potentially bypassing an expensive move to a newer process node and unlocking even more functionality from the same package.

These downscaling issues are not limited to traditional CMOS technologies but extend to Quantum Computers. Due to the highly heterogeneous nature of Quantum ICs, and especially their requirement of low qubit decoherence noise, we require high-density connections from the Qubit layer to the Microelectronics Control layer while maintaining appropriate spacial separation between the two. In this project, the qubit layer is comprised of Diamond Colour Centers in a Photonic IC with other optical components such as SNSPDs, and MEMS switches. On the other hand, the microelectronics control layer is a Cryogenic CMOS chip.

The main goal of this project is to design an Interposer and related technologies like Through Silicon Vias (TSVs) and Microbumps to successfully integrate these two chiplets in a single 3D assembly. We conduct thermal analysis of multiple 3D assembly designs using Finite Element Modelling to derive optimum fabrication specifications. Subsequently, fabrication recipes are developed and optimised for TSV etching, coating, and patterning with superconductive sidewall liners. Recipes are also developed to fabricate Indium Microbumps using techniques like evaporation, liftoff, and atmospheric reflow. Utilizing these microbumps, we conduct cold-compression flip-chip experiments. Finally, we establish cryogenic measurement setups to electrically characterize these fabricated devices.

Quantum sensing technology has emerged as a promising field with superior sensitivity and accuracy in magnetic field sensing compared to conventional technologies. This breakthrough offers significant prospects in the biomedical sector, particularly in the realm of medical imaging.

This project focuses on the implementation of quantum sensing using an array of single Nitrogen Vacancy (NV) centers combined with an array of Single Photon Avalanche Diodes (SPADs). SPADs are available in various technologies and forms. To identify the optimal SPAD for this specific application, different SPADs with diverse parameters are designed on a chip using standard 40 nm TSMC process. These parameters include active area, active area shape and metal shielding.

The research aims to validate and characterize the performance of these distinct SPADs. However, during the validation tests, it was observed that the SPADs did not meet the criteria. The presence of ESD diodes on the chip introduced a low resistance current path, thereby hindering the characterisation process of the SPADs. Solutions to fix this problem and improve the system are provided.

The documented validation methods include general chip testing, establishing the I-V curves of the SPADs and avalanche and quenching testing. In addition, the characterisation methods for junction capacitance, dark count rate (DCR), photon detection probability (PDP) and time jitter are given.

For characterizing DCR and PDP a readout system is designed. It consists of an analog-to-digital converter (ADC), FPGA and Arduino. The data is communicated continuously to a PC. The ADC is not fully tested. On the other hand, the FPGA and Arduino are tested and verified to be sufficient for the DCR measurements. The readout system is too inaccurate for PDP measurements. A recommendation on how to make the readout system sufficient for PDP is given.

Color centers in diamond offer exciting opportunities for implementing an effective solid-state spinphoton interface. Access to and control of spin-photon interaction can help realize a scalable, modular quantum computer using the color center spins. A large magnetic field is needed for splitting the color center spin states, enabling definition of the qubits. In addition to the large, global magnetic field (∼1T), applying a small and tunable magnetic field (order of mT) in the vicinity of individual color centers is advantageous as it allows for external field inhomogeneity compensation and multiplexing of the qubit driving frequency. Local tuning of the magnetic field magnitude might be achieved by driving DC currents through microscopic coils located in close proximity of the respective color centers. Since the systems must be located at cryogenic temperatures, cooling power is limited. Superconducting coils are therefore considered for local tuning instead of conventional metal. Design requirements for the local tuning coils depend strongly on design choices of the external magnet, externally applied field magnitude, number of FDM channels and coil distance from the color center. In order to find a design process that easily accounts for changes in these choices, the utilization of FEM physics simulations is studied. Two simulation methods are considered and tested in COMSOL Multiphysics. The first method is called 𝐻-𝜙-formulation, which is considered for optimizing the coil geometry. This method is based on a classical description of superconductivity and is shown here to have potential for simulating large coil structures. The second method allows for 3D simulation of superconductors based on the time-dependent Ginzburg-Landau (TDGL) equations. This method is considered with the goal of predicting changes in critical current density due to differences in cross-section dimensions. It is shown that this method can qualitatively reproduce transport characteristics of microscopic wires when no magnetic field is applied. When a magnetic field is applied, the observed vortex dynamics and resistivity correspond to that of material with no impurities or defects. Adding impurities in the form of geometrical deformations is shown here to be possible. However, further development on the method is required in order to overcome computational limitations and to determine unknown factors such as the impurity density and pinning forces. Until such time, the design procedure recommended in this thesis is based on 𝐻-𝜙-formulation simulations in combination with measurements of straight transport lines for critical current density characterization. Fabrication of NbTiN films is successfully tested by patterning coil-shaped structures, followed by DC magnetron sputtering and liftoff. The coil structures will be used to measure deviations from the expected critical current density due to geometry and to validate the recommended design procedure. Straight lines NbTiN geometries are fabricated with the purpose of finding the critical current density as a function of cross-section dimensions and magnetic field. These samples will be used to select the cross-section dimensions that deliver optimal critical current density, which will consequently be used in simulation to optimize the geometry.

A new antenna measurement setup, the Antenna Dome, is being developed, which can provide real time antenna and beamformer measurements. In order to be able to validate this setup, an existing beamforming system will be will be extensively studied and characterized. Multiple measurement setups will be used, providing multiple measured characteristics. The result is an accurate statistical model for the steering system, and a comprehensive error model for the complete beamforming system, including the provided antenna array. This model will help in validating the functionality of the Antenna Dome, and ultimately will help in its further development.

In this thesis, the realization and qualification of an anechoic dome chamber for 5G antenna’s is discussed. As with audio, where no echoes or noise from outside is wanted when listening to music, when characterizing an antenna it must be prevented to get internal reflections or electromagnetic (EM) radiation from outside. For this reason, a measurement setup was simulated, using that setup, different absorbers were tested and characterized. And a Faraday cage shielding is designed and evaluated, to remove EM interference. To make the anechoic chamber physically possible, rebuilding the minidome was also required, so that the absorber and Faraday cage could be mounted on the inner wand of the dome. Eventually, a suitable test environment for 5G antenna’s is build. In the end, the assessment of the absorbing materials was completed, and the chamber achieved all requirements. Despite the space of improvement, the idea of building an anechoic chamber is successfully verified.